Refrigeration apparatus

ABSTRACT

A refrigeration apparatus includes a refrigerant circuit having a main circuit performing a refrigeration cycle and a branch circuit which branches part of high-pressure liquid refrigerant flowing through the main circuit and leads the part of high-pressure liquid refrigerant from a high-pressure part of the main circuit to part of the main circuit having a pressure lower than that of the high-pressure part. The branch circuit is connected to a cooler configured to cool a power element(s) of a power supply device supplying power to drivers of components of the refrigerant circuit by refrigerant. In the refrigeration apparatus, an adjusting mechanism configured to adjust the state of refrigerant flowing through the branch circuit and adjust the temperature of refrigerant passing through the cooler to a target temperature is provided.

TECHNICAL FIELD

The present invention relates to a refrigeration apparatus in which apower element(s) of a power supply device configured to supply power tocomponents of a refrigerant circuit is cooled by refrigerant.

BACKGROUND ART

Conventionally, a refrigeration apparatus has been known, in which apower element(s) used for a power supply device of, e.g., a compressoris cooled by refrigerant of a refrigerant circuit. For example, PatentDocument 1 discloses a refrigeration apparatus in which a coolerconfigured to cool a power element(s) is arranged in a branch flow pathbranched from part of a main circuit between a condenser and anexpansion valve and joining an inlet pipe of the compressor. A capillarytube is provided upstream of the cooler of the branch flow path. In therefrigeration apparatus, part of refrigerant condensed in the condenserand flowing toward the expansion valve flows into the branch flow path.Then, after the pressure of such refrigerant is reduced by the capillarytube, the refrigerant flows into the cooler. The refrigerant flowinginto the cooler cools the power element(s) in the cooler. Subsequently,the refrigerant joins refrigerant flowing through the inlet pipe of thecompressor, and flows into the compressor.

CITATION LIST Patent Document

-   PATENT DOCUMENT 1: Japanese Utility Model Publication No. S61-076267

SUMMARY OF THE INVENTION Technical Problem

The amount of heat generation of the power element of the power supplydevice is significantly changed depending on a usage status and a usageenvironment. In the foregoing refrigeration apparatus, since thepressure of refrigerant of the branch flow path is reduced by thecapillary tube, a pressure reduction amount by the capillary tube isconstant. Thus, the amount and pressure of refrigerant flowing into thecooler are determined by the rotational speed of the compressorcontrolled depending on a load of a utilization-side heat exchanger, andcannot be changed depending on the amount of heat generation of thepower element. This may results in deficiency or excess of a coolingcapacity of refrigerant in the cooler.

The present invention has been made in view of the foregoing, and it isan objective of the present invention to improve, in a refrigerationapparatus including a cooler configured to cool a power element(s) byrefrigerant, efficiency of cooling the power element(s) by therefrigerant in the cooler.

Solution to the Problem

A first aspect of the invention is intended to a refrigeration apparatusincluding a refrigerant circuit (10) having a main circuit (10A) inwhich a compressor (11), a heat-source-side heat exchanger (12), anexpansion mechanism (13), and a utilization-side heat exchanger (14) areconnected together to perform a refrigeration cycle, a branch circuit(10B) which branches part of high-pressure liquid refrigerant flowingthrough the main circuit (10A) and leads the part of high-pressureliquid refrigerant from a high-pressure part of the main circuit (10A)to part of the main circuit (10A) having a pressure lower than that ofthe high-pressure part, a power supply device (30) including a powerelement (37) and supplying power to a driver of a component of therefrigerant circuit (10), and a cooler (16) connected to the branchcircuit (10B) and cooling the power element (37) by refrigerant flowingthrough the branch circuit (10B). In addition, the refrigerationapparatus includes an adjusting mechanism (90) configured to adjust astate of refrigerant flowing through the branch circuit (10B) and adjusta temperature of refrigerant passing through the cooler (16) to a targettemperature.

In the first aspect of the invention, the cooler (16) is provided in thebranch circuit (10B) which branches part of high-pressure liquidrefrigerant flowing through the main circuit (10A) and leads the part ofhigh-pressure liquid refrigerant from the high-pressure part of the maincircuit (10A) to part of the main circuit (10A) having the pressurelower than that of the high-pressure part. In addition, in the firstaspect of the invention, the power supply device (30) supplies power tothe driver of the component of the refrigerant circuit (10). In thecooler (16), refrigerant flowing into the branch circuit (10B) absorbsheat from the power element (37) of the power supply device (30) to coolthe power element (37). In addition, the adjusting mechanism (90)adjusts the state of refrigerant flowing through the branch circuit(10B) and adjusts the temperature of refrigerant passing through thecooler (16) to the target temperature. This adjusts the temperature ofthe cooler (16).

Note that “to cool the power element (37)” includes the case where thepower element (37) is indirectly cooled through surrounding componentssuch as a substrate on which the power element (37) is mounted.

A second aspect of the invention is intended to the refrigerationapparatus of the first aspect of the invention, in which the adjustingmechanism (90) includes a throttle mechanism (17, 27) connected to oneend of the cooler (16) of the branch circuit (10B), a throttle valve(18, 28) which is connected to the other end of the cooler (16) of thebranch circuit (10B) and a degree of opening of which is adjustable, andan opening degree adjuster (52, 59) adjusting the degree of opening ofthe throttle valve (18, 28) such that an evaporation temperature ofrefrigerant in the cooler (16) reaches a target temperature.

In the second aspect of the invention, a flow path width is reduced bythe throttle mechanism at the one end of the cooler (16) of the branchcircuit (10B). A flow path width is reduced by the throttle valve (18,28), the degree of opening of which is adjusted by the opening degreeadjuster (52, 59), at the other end of the cooler (16) of the branchcircuit (10B). The opening degree adjuster (52, 59) adjusts the degreeof opening of the throttle valve (18, 28) such that the evaporationtemperature of refrigerant in the cooler (16) reaches the targettemperature, thereby adjusting the temperature of the cooler (16) to adesired temperature.

A third aspect of the invention is intended to the refrigerationapparatus of the second aspect of the invention, in which the throttlevalve (18) is provided downstream of the cooler (16), the throttlemechanism (17) is provided upstream of the cooler (16), and a degree ofopening of the throttle mechanism (17) is adjustable, and the adjustingmechanism (90) further includes a throttle mechanism adjuster (53)adjusting the degree of opening of the throttle mechanism (17) such thata degree of superheating of refrigerant at an outlet of the cooler (16)reaches a target degree of superheating.

In the third aspect of the invention, the degree of opening of thethrottle valve (18) provided downstream of the cooler (16) is adjusted,and therefore the temperature of the cooler (16) is adjusted to thedesired temperature. On the other hand, the degree of opening of thethrottle mechanism (17) provided upstream of the cooler (16) is adjustedby the throttle mechanism adjuster (53), and therefore the degree ofsuperheating of refrigerant after the refrigerant passes through thecooler (16) reaches the target degree of superheating. Thus,moisturizing of refrigerant led to the compressor (11) is prevented.

A fourth aspect of the invention is intended to the refrigerationapparatus of the third aspect of the invention, in which the openingdegree adjuster (52) adjusts, upon a start of the refrigerationapparatus, the degree of opening of the throttle valve (18) to a degreeof opening larger than an opening degree adjustable range of a normaloperation, and the throttle mechanism adjuster (53) adjusts, upon thestart of the refrigeration apparatus, the degree of opening of thethrottle mechanism (17) to a degree of opening larger than an openingdegree adjustable range of the normal operation.

Upon the start of the refrigeration apparatus, only liquid refrigerantdoes not flow into the branch circuit (10B), but refrigerant containinga relatively-large amount of gas refrigerant flows into the branchcircuit (10B). Thus, unevenness in temperature of the cooler (16) islikely to occur, and it is highly likely that the power element (37)cannot be sufficiently cooled. In addition, if the amount of refrigerantflowing into the branch circuit (10B) is small, it takes time forrefrigerant to reach the cooler (16) after the start of therefrigeration apparatus, and the power element (37) cannot be cooledduring such a time.

In the fourth aspect of the invention, upon the start of therefrigeration apparatus, the opening degree adjuster (52) adjusts thedegree of opening of the downstream-side throttle valve (18) to thedegree of opening larger than that of the normal operation, and thethrottle mechanism adjuster (53) adjusts the degree of opening of theupstream-side throttle mechanism (17) to the degree of opening largerthan that of the normal operation. As in the foregoing, by adjusting,upon the start of the refrigeration apparatus, the degree of opening ofthe upstream-side throttle mechanism (17) and the degree of opening ofthe downstream-side throttle valve (18) to the degree of opening largerthan that of the normal operation, an easy flow of refrigerant into thebranch circuit (10B) is allowed, and refrigerant promptly reaches thecooler (16).

A fifth aspect of the invention is intended to the refrigerationapparatus of the third or fourth aspect of the invention, which furtherincludes a stop controller (97) configured to, upon stoppage of therefrigeration apparatus, control at least one of the degrees of openingof the throttle valve (18) and the throttle mechanism (17) to afully-closed state.

When the throttle valve (18) and the throttle mechanism (17) are openedupon the stoppage of the refrigeration apparatus, refrigerant continuesflowing until a pressure in the branch circuit (10B) is balanced. Thus,for a certain time after the stoppage of the refrigeration apparatus,refrigerant flows into the cooler (16) although the power element (37)does not generate heat. As a result, there is a possibility that dewcondensation occurs in the cooler (16), and therefore the power element(37) is broken down.

In the fifth aspect of the invention, upon the stoppage of therefrigeration apparatus, the stop controller (97) controls the at leastone of the degrees of opening of the throttle valve (18) and thethrottle mechanism (17) to the fully-closed state. Thus, refrigerant nolonger flows into the cooler (16) after the stoppage of therefrigeration apparatus. As a result, a decrease in temperature of thecooler (16) is reduced.

A sixth aspect of the invention is intended to the refrigerationapparatus of any one of the third to fifth aspects of the invention,which further includes a fixed throttle (4) connected in parallel to thethrottle mechanism (17).

The throttle mechanism (17) provided upstream of the cooler (16) isconfigured such that the degree of opening thereof is adjustable by thethrottle mechanism adjuster (53) However, if the throttle mechanism (17)is broken down, the degree of opening thereof cannot be adjusted. Thus,if the degree of opening of the throttle mechanism (17) is fixed to arelatively-small degree of opening, the pressure of refrigerant issignificantly reduced on an upstream side of the cooler (16). That is,the evaporation pressure of refrigerant in the cooler (16) issignificantly reduced. For the foregoing reason, there is a possibilitythat the temperature of refrigerant circulating through the cooler (16)is decreased, resulting in excess of a cooling capacity of the cooler(16). In addition, if the flow rate of refrigerant flowing into thecooler (16) is too low, the cooling capacity of the cooler (16) may bedeficient.

In the sixth aspect of the invention, the fixed throttle (4) connectedin parallel to the throttle mechanism (17) is provided. If the degree ofopening of the throttle mechanism (17) is fixed to the relatively-smalldegree of opening due to the breakdown of the throttle mechanism (17),refrigerant passes through a flow path formed by the fixed throttle (4)and flows into the cooler (16). Thus, even if the throttle mechanism(17) is broken down, the extremely-low evaporation pressure ofrefrigerant in the cooler (16) is prevented. As a result, the excessivedecrease in temperature of refrigerant circulating through the cooler(16) is prevented. In addition, the significantly-low flow rate ofrefrigerant flowing into the cooler (16) is prevented.

A seventh aspect of the invention is intended to the refrigerationapparatus of any one of the third to sixth aspects of the invention,which further includes a fixed throttle (5) connected in series with thefirst throttle valve (18).

The throttle valve (18, 28) provided downstream of the cooler (16) isconfigured such that the degree of opening thereof is adjustable by theopening degree adjuster (52, 59). However, if the throttle valve (18,28) is broken down, the degree of opening thereof cannot be adjusted.Thus, if the degree of opening of the throttle valve (18, 28) is fixedto a relatively-large degree of opening, a differential pressure in thethrottle valve (18, 28) is significantly low, and the pressure ofrefrigerant flowing into the cooler (16) is close to the pressure ofrefrigerant at an outlet of the branch circuit (10B). That is, theevaporation pressure of refrigerant in the cooler (16) is significantlyreduced. For the foregoing reason, there is a possibility that thetemperature of the cooler (16) is decreased, resulting in excess of thecooling capacity of the cooler (16). In addition, if the degree ofopening of the throttle valve (18, 28) is large, the amount ofrefrigerant flowing out from the cooler (16) is increased. Thus,refrigerant flows out from the cooler (16) before refrigerant flowinginto the cooler (16) exchanges sufficient heat with the power element(37). That is, refrigerant branched from a main flow uselessly passesthrough the cooler (16).

In the seventh aspect of the invention, the fixed throttle (5) connectedin series with the throttle valve (18, 28) is provided. Thus, even ifthe degree of opening of the throttle valve (18, 28) is fixed to therelatively-large degree of opening due to the breakdown of the throttlevalve (18, 28), the pressure of refrigerant is reduced by the fixedthrottle (5). Since the significantly-low evaporation pressure ofrefrigerant in the cooler (16) is prevented, the excessive decrease intemperature of refrigerant circulating through the cooler (16) isprevented. In addition, the capillary tube (5) prevents the amount ofrefrigerant flowing out from the cooler (16) from being significantlyincreased. Thus, refrigerant flowing into the cooler (16) flows out fromthe cooler (16) after the sufficient heat exchange with the powerelement (37).

An eighth aspect of the invention is intended to the refrigerationapparatus of any one of the second to seventh aspects of the invention,which includes a detector (41, 46, 47, 48) configured to detect aphysical amount to be an indicator for a possibility of occurrence ofdew condensation in the power element (37) or a surrounding component(16, 71) thereof; and a forcible opening degree reducer (55) configuredto, when a detection value of the detector (41, 46, 47, 48) indicates adew condensation state in which the dew condensation is highly likely tooccur in the power element (37) or the surrounding component (16, 71)thereof, forcibly reduce the degree of opening of the throttle valve(18, 28) on behalf of the opening degree adjuster (52, 59).

In the eighth aspect of the invention, when the detection value of thedetector (41, 46, 47, 48) indicates the dew condensation state in whichthe dew condensation is highly likely to occur in the power element (37)or the surrounding component (16, 71) thereof, the forcible openingdegree reducer (55) forcibly reduces the degree of opening of thethrottle valve (18, 28) on behalf of the opening degree adjuster (52,59). Thus, since the amount of refrigerant passing through the cooler(16) is reduced, the amount of heat absorbed by refrigerant in thecooler (16) is reduced, and therefore the excessive decrease intemperature of the power element (37) or the cooler (16) is reduced.

A ninth aspect of the invention is intended to the refrigerationapparatus of the eighth aspect of the invention, in which the detectorincludes a temperature sensor (46) provided in the power element (37) orthe surrounding component (16, 71) thereof, and an air temperaturesensor (41) detecting a temperature of air around the power supplydevice (30), and the forcible opening degree reducer (55) is configuredto, when the detection value of the temperature sensor (46) is lowerthan the detection value of the air temperature sensor (41) and it isdetermined that the dew condensation state is established, forciblyreduce the degree of opening of the throttle valve (18, 28) on behalf ofthe opening degree adjuster (52, 59).

In the ninth aspect of the invention, the temperature sensor (46)provided in the power element (37) or the surrounding component (16, 71)thereof, and the air temperature sensor (41) detecting the temperatureof air around the power supply device (30) are used as the detectors.

Since it is practically impossible that the relative humidity of airaround the power supply device (30)) reaches 100%, the dew-pointtemperature of air around the power supply device (30) is lower than thetemperature of such air (dry-bulb temperature of air around the powersupply device (30)). In the state in which the detection value of thetemperature sensor (46) is lower than the detection value of the airtemperature sensor (41), the temperature of the power element (37) orthe surrounding component (16, 71) thereof is close to the dew-pointtemperature of air around the power supply device (30). Thus, it can beassumed that the dew condensation is highly likely to occur in the powerelement (37) or surrounding component (16, 71) thereof.

Thus, in the ninth aspect of the invention, when the detection value ofthe temperature sensor (46) is lower than the detection value of the airtemperature sensor (41), the forcible opening degree reducer (55)forcibly reduces the degree of opening of the throttle valve (18, 28) onbehalf of the opening degree adjuster (52, 59).

A tenth aspect of the invention is intended to the refrigerationapparatus of the eighth aspect of the invention, in which the detectorincludes a temperature sensor (46) provided in the power element (37) orthe surrounding component (16, 71) thereof, and an air temperaturesensor (41) detecting a temperature of air around the power supplydevice (30), and the forcible opening degree reducer (55) is configuredto, when a temperature obtained by adding a preset temperature increasefrom an installation part of the temperature sensor (46) to anelectrical connection part of the power element (37) to the detectionvalue of the temperature sensor (46) is lower than the detection valueof the air temperature sensor (41) and it is determined that the dewcondensation state is established, forcibly reduce the degree of openingof the throttle valve (18, 28) on behalf of the opening degree adjuster(52, 59).

Even under the temperature environment under which the dew condensationoccurs around the cooler (16) during the operation of the refrigerationapparatus, the electrical connection part of the power element (37)where a short circuit may occur due to adherence of dew condensationwater may not actually be, because of heat generation of the powerelement (37), under the temperature environment under which the dewcondensation occurs.

Thus, in the tenth aspect of the invention, when the estimatedtemperature of the electrical connection part of the power element (37)where the short circuit may occur due to the adherence of dewcondensation water is lower than an air temperature, the forcibleopening degree reducer (55) forcibly reduces the degree of opening ofthe throttle valve (18, 28).

An eleventh aspect of the invention is intended to the refrigerationapparatus of the eighth aspect of the invention, in which the detectorincludes a temperature sensor (46) provided in the power element (37) orthe surrounding component (16, 71) thereof, and an air temperaturesensor (41) detecting a temperature of air around the power supplydevice (30), and the forcible opening degree reducer (55) is configuredto, when the detection value of the temperature sensor (46) is lowerthan a dew-point temperature corresponding to a preset referencerelative humidity at an air temperature detected by the air temperaturesensor (41) and it is determined that the dew condensation state isestablished, forcibly reduce the degree of opening of the throttle valve(18, 28) on behalf of the opening degree adjuster (52, 59).

In the eleventh aspect of the invention, the temperature sensor (46)provided in the power element (37) or the surrounding component (16, 71)thereof, and the air temperature sensor (41) detecting the temperatureof air around the power supply device (30) are used as the detectors.When the detection value of the temperature sensor (46) is lower thanthe dew-point temperature of air around the power supply device (30)which is calculated based on the detection value of the air temperaturesensor (41) and the predetermined reference humidity preset as therelative humidity of air around the power supply device (30)considering, e.g., installation environment and a usage time, theforcible opening degree reducer (55) forcibly reduces the degree ofopening of the throttle valve (18, 28) on behalf of the opening degreeadjuster (52, 59).

A twelfth aspect of the invention is intended to the refrigerationapparatus of the eighth aspect of the invention, in which the detectorincludes a humidity sensor (47) detecting a relative humidity of airaround the power element (37), and the forcible opening degree reducer(55) is configured to, when the detection value of the humidity sensor(47) is higher than a predetermined upper limit and it is determinedthat the dew condensation state is established, forcibly reduce thedegree of opening of the throttle valve (18, 28) on behalf of theopening degree adjuster (52, 59).

In the twelfth aspect of the invention, the humidity sensor (47) detectsthe relative humidity of air around the power element (37). In addition,when the detection value of the humidity sensor (47) is higher than thepredetermined upper limit, the forcible opening degree reducer (55)forcibly reduces the degree of opening of the throttle valve (18, 28) onbehalf of the opening degree adjuster (52, 59).

A thirteenth aspect of the invention is intended to the refrigerationapparatus of the eighth aspect of the invention, in which the detectorincludes a humidity sensor (48) detecting a relative humidity of airaround the power supply device (30), an air temperature sensor (41)detecting a temperature of air around the power supply device (30), anda temperature sensor (46) provided in the power element (37) or thesurrounding component (16, 71) thereof, and the forcible opening degreereducer (55) is configured to, when the detection value of thetemperature sensor (46) is lower than a dew-point temperature calculatedbased on the relative humidity detected by the humidity sensor (48) andthe air temperature detected by the air temperature sensor (41),forcibly reduce the degree of opening of the throttle valve (18, 28) onbehalf of the opening degree adjuster (52, 59).

In the thirteenth aspect of the invention, the humidity sensor (48)detecting the relative humidity of air around the power supply device(30), the air temperature sensor (41) detecting the temperature of airaround the power supply device (30), and the temperature sensor (46)provided in the power element (37) or the surrounding component (16, 71)thereof are used as the detectors. When the temperature around the powerelement (37) is lower than the dew-point temperature of air calculatedbased on the temperature and humidity of the air (outdoor air) beforethe air is cooled by the cooler (16), the forcible opening degreereducer (55) forcibly reduces the degree of opening of the throttlevalve (18, 28) on behalf of the opening degree adjuster (52, 59).

A fourteenth aspect of the invention is intended to the refrigerationapparatus of any one of the second to seventh aspects of the invention,which further includes a dew condensation sensor (45) detecting dewcondensation in the power element (37) or the surrounding component (16,71) thereof; and a forcible opening degree reducer (55) configured to,when a detection value of the dew condensation sensor (45) indicates adew condensation state in which dew condensation occurs in the powerelement (37) or the surrounding component (16, 71) thereof, forciblyreduce the degree of opening of the throttle valve (18, 28) on behalf ofthe opening degree adjuster (52, 59).

In the fourteenth aspect of the invention, the forcible opening degreereducer (55) forcibly reduces the degree of opening of the throttlevalve (18, 28) on behalf of the opening degree adjuster (52, 59) notwhen it is assumed that the dew condensation occurs in the power element(37) or the surrounding component (16, 71) thereof, but when the dewcondensation actually occurs in the power element (37) or thesurrounding component (16, 71) thereof. This reduces the amount ofrefrigerant passing through the cooler (16). Thus, the amount of heatabsorbed by refrigerant in the cooler (16) is reduced, and therefore theexcessive decrease in temperature of the power element (37) or thecooler (16) is reduced.

A fifteenth aspect of the invention is intended to the refrigerationapparatus of any one of the first to fourteenth aspects of theinvention, which further includes a closing unit (6) configured to closethe branch circuit (10B) upon power shutdown that a power supply to thepower supply device (30) is shut down.

When the power supply to the power supply device (30) is shut down dueto, e.g., a blackout, a power supply to the power element (37) is alsoshut down. As a result, the power element (37) no longer generates heat.Meanwhile, in the branch circuit (10B), refrigerant continues flowinguntil the pressure is balanced. Although the power element (37) does notgenerate heat, refrigerant continues circulating through the cooler(16). As a result, there is a possibility that the temperature of thecooler (16) is decreased to the temperature at which the dewcondensation occurs.

In the fifteenth aspect of the invention, when the power supply to thepower supply device (30) is shut down, the closing unit (6) closes thebranch circuit (10B). This prevents the refrigerant circulation throughthe cooler (16). Thus, the decrease in temperature of the cooler (16) isreduced.

A sixteenth aspect of the invention is intended to the refrigerationapparatus of the fifteenth aspect of the invention, in which the closingunit (6) is configured by a solenoid valve (6 a) provided in the branchcircuit (10B) and switching to a closed state upon the power shutdown.

In the sixteenth aspect of the invention, when the power supply to thepower supply device (30) is shut down, the solenoid valve (6 a) closesthe branch circuit (10B).

A seventeenth aspect of the invention is intended to the refrigerationapparatus of the third aspect of the invention, which further includes apower shutdown adjusting unit (6 b) configured to, upon power shutdownthat a power supply to the power supply device (30) is shut down, usepower generated in a driver of the compressor (11) by rotation of thecompressor (11) to adjust at least one of the degrees of opening of thethrottle valve (18) and the throttle mechanism (17) to a fully-closedstate.

In the seventeenth aspect of the invention, when the power supply to thepower supply device (30) is shut down, the power shutdown adjusting unit(6 b) uses power generated in the driver by the rotation (rotation usinginertia or reverse rotation using a refrigerant pressure) of thecompressor (11) to adjust the at least one of the degrees of opening ofthe throttle valve (18) and the throttle mechanism (17) to thefully-closed state. Then, the power shutdown adjusting unit (6 b) closesthe branch circuit (10B).

An eighteenth aspect of the invention is intended to the refrigerationapparatus of any one of the first to seventeenth aspects of theinvention, which further includes a pump-down controller (98) configuredto control the expansion mechanism (13) and at least one of the throttlevalve (18) and the throttle mechanism (17) to the fully-closed state toperform a pump-down operation in which refrigerant is stored in theheat-source-side heat exchanger (12), and estimate an overheating pointbringing about an overheating state in which a temperature of the powerelement (37) is highly likely to exceed a predetermined upper limit tocomplete the pump-down operation before the overheating point.

When the pump-down operation is performed, the at least one of thethrottle valve (18) and the throttle mechanism (17) is switched to thefully-closed state to close the branch circuit (10B). Thus, refrigerantno longer flows into the cooler (16). Although the power element (37)cannot be cooled by the cooler (16) and the temperature of the powerelement (37) is increased, refrigerant does not flow into the cooler(16), and therefore the overheating state of the power element (37)cannot be estimated based on a refrigerant state. As a result, there isa possibility that the power element (37) enters the overheating stateduring the pump-down operation.

Thus, in the eighteenth aspect of the invention, the pump-downcontroller (98) is provided, which is configured to perform thepump-down operation, estimate the overheating point bringing about theoverheating state of the power element (37) during the pump-downoperation, and complete the pump-down operation before the overheatingpoint. Thus, the pump-down operation is completed before the powerelement (37) enters the overheating state.

A nineteenth aspect of the invention is intended to the refrigerationapparatus of any one of the first to eighteenth aspects of theinvention, which further includes a start interrupting unit (99)configured to, when the dew condensation is highly likely to occur inthe cooler (16), interrupt the start of the refrigeration apparatus.

Upon the stoppage of the refrigeration apparatus, the dew condensationmay be highly likely to occur in the cooler (16) depending on, e.g., achange in environment. If the refrigeration apparatus is started in sucha state, there is a possibility that a short circuit is caused in, e.g.,the electrical connection part of the power element (37).

In the nineteenth aspect of the invention, when the dew condensation ishighly likely to occur in the cooler (16), the start interrupting unit(99) interrupts the start of the refrigeration apparatus. Thus, thestart of the refrigeration apparatus is allowed only when the dewcondensation is not highly likely to occur in the cooler (16).

A twentieth aspect of the invention is intended to the refrigerationapparatus of any one of the second to seventh aspects of the invention,which further includes a detector (41, 46, 47, 48) configured to detecta physical amount to be an indicator for a possibility of occurrence ofdew condensation in the power element (37) or a surrounding component(16, 71) thereof; and a temperature increaser (91) configured to, when adetection value of the detector (41, 46, 47, 48) indicates a dewcondensation state in which the dew condensation is highly likely tooccur in the power element (37) or the surrounding component (16, 71)thereof, increase a temperature of the power element (37).

In the twentieth aspect of the invention, when the detection value ofthe detector (41, 46, 47, 48) indicates the dew condensation state inwhich the dew condensation is highly likely to occur in the powerelement (37) or the surrounding component (16, 71) thereof, thetemperature increaser (91) increases the temperature of the powerelement (37). This increase the temperature of the surrounding component(16, 71) of the power element (37).

A twenty-first aspect of the invention is intended to the refrigerationapparatus of the twentieth aspect of the invention, in which thedetector includes a temperature sensor (46) provided in the powerelement (37) or the surrounding component (16, 71) thereof, and an airtemperature sensor (41) detecting a temperature of air around the powersupply device (30), and the temperature increaser (91) is configured to,when the detection value of the temperature sensor (46) is lower thanthe detection value of the air temperature sensor (41) and it isdetermined that the dew condensation state is established, increase thetemperature of the power element (37).

In the twenty-first aspect of the invention, the temperature sensor (46)provided in the power element (37) or the surrounding component (16, 71)thereof, and the air temperature sensor (41) detecting the temperatureof air around the power supply device (30) are used as the detectors.

Since it is practically impossible that the relative humidity of airaround the power supply device (30) reaches 100%, the dew-pointtemperature of air around the power supply device (30) is lower than thetemperature of such air (dry-bulb temperature of air around the powersupply device (30)). In the state in which the detection value of thetemperature sensor (46) is lower than the detection value of the airtemperature sensor (41), the temperature of the power element (37) orthe surrounding component (16, 71) thereof is close to the dew-pointtemperature of air around the power supply device (30). Thus, it can beassumed that the dew condensation is highly likely to occur in the powerelement (37) or surrounding component (16, 71) thereof.

Thus, in the twenty-first aspect of the invention, when the detectionvalue of the temperature sensor (46) is lower than the detection valueof the air temperature sensor (41), the temperature increaser (91)increases the temperature of the power element (37).

A twenty-second aspect of the invention is intended to the refrigerationapparatus of the twentieth aspect of the invention, in which thedetector includes a temperature sensor (46) provided in the powerelement (37) or the surrounding component (16, 71) thereof, and an airtemperature sensor (41) detecting a temperature of air around the powersupply device (30), and the temperature increaser (91) is configured to,when a temperature obtained by adding a preset temperature increase froman installation part of the temperature sensor (46) to an electricalconnection part of the power element (37) to the detection value of thetemperature sensor (46) is lower than the detection value of the airtemperature sensor (41) and it is determined that the dew condensationstate is established, increase the temperature of power element (37).

Even under the temperature environment under which the dew condensationoccurs around the cooler (16) during the operation of the refrigerationapparatus, the electrical connection part of the power element (37)where the short circuit may occur due to the adherence of dewcondensation water may not actually be, because of the heat generationof the power element (37), under the temperature environment under whichthe dew condensation occurs.

Thus, in the twenty-second aspect of the invention, when the estimatedtemperature of the electrical connection part of the power element (37)where the short circuit may occur due to the adherence of dewcondensation water is lower than the air temperature, the temperatureincreaser (91) increases the temperature of the power element (37).

A twenty-third aspect of the invention is intended to the refrigerationapparatus of the twentieth aspect of the invention, in which thedetector includes a temperature sensor (46) provided in the powerelement (37) or the surrounding component (16, 71) thereof, and an airtemperature sensor (41) detecting a temperature of air around the powersupply device (30), and the temperature increaser (91) is configured to,when the detection value of the temperature sensor (46) is lower than adew-point temperature corresponding to a preset reference relativehumidity at an air temperature detected by the air temperature sensor(41) and it is determined that the dew condensation state isestablished, increase the temperature of the power element (37).

In the twenty-third aspect of the invention, the temperature sensor (46)provided in the power element (37) or the surrounding component (16, 71)thereof, and the air temperature sensor (41) detecting the temperatureof air around the power supply device (30) are used as the detectors.When the detection value of the temperature sensor (46) is lower thanthe dew-point temperature of air around the power supply device (30)which is calculated based on the detection value of the air temperaturesensor (41) and the predetermined reference humidity preset as therelative humidity of air around the power supply device (30)considering, e.g., the installation environment and the usage time, thetemperature increaser (91) increases the temperature of the powerelement (37).

A twenty-fourth aspect of the invention is intended to the refrigerationapparatus of the twentieth aspect of the invention, in which thedetector includes a humidity sensor (47) detecting a relative humidityof air around the power element (37), and the temperature increaser (91)is configured to, when the detection value of the humidity sensor (47)is higher than a predetermined upper limit and it is determined that thedew condensation state is established, increase the temperature of thepower element (37).

In the twenty-fourth aspect of the invention, the humidity sensor (47)is used as the detector, and detects the relative humidity of air aroundthe power element (37). In addition, when the detection value of thehumidity sensor (47) is higher than the predetermined upper humiditylimit, the temperature increaser (91) increases the temperature of thepower element (37).

A twenty-fifth aspect of the invention is intended to the refrigerationapparatus of the twentieth aspect of the invention, in which thedetector includes a humidity sensor (48) detecting a relative humidityof air around the power supply device (30), an air temperature sensor(41) detecting a temperature of air around the power supply device (30),and a temperature sensor (46) provided in the power element (37) or thesurrounding component (16, 71) thereof, and the temperature increaser(91) is configured to, when the detection value of the temperaturesensor (46) is lower than a dew-point temperature calculated based onthe relative humidity detected by the humidity sensor (48) and the airtemperature detected by the air temperature sensor (41) and it isdetermined that the dew condensation state is established, increase thetemperature of the power element (37).

In the twenty-fifth aspect of the invention, the humidity sensor (48)detecting the relative humidity of air around the power supply device(30), the air temperature sensor (41) detecting the temperature of airaround the power supply device (30), and the temperature sensor (46)provided in the power element (37) or the surrounding component (16, 71)thereof are used as the detectors. When the temperature around the powerelement (37) is lower than the dew-point temperature of air calculatedbased on the temperature and humidity of the air (outdoor air) beforethe air is cooled by the cooler (16), the temperature increaser (91)increases the temperature of the power element (37).

A twenty-sixth aspect of the invention is intended to the refrigerationapparatus of any one of the second to seventh aspects of the invention,which further includes a dew condensation sensor (45) detecting dewcondensation in the power element (37) or the surrounding component (16,71) thereof; and a temperature increaser (91) configured to, when adetection value of the dew condensation sensor (45) indicates a dewcondensation state in which dew condensation occurs in the power element(37) or the surrounding component (16, 71) thereof, increase atemperature of the power element (37).

In the twenty-sixth aspect of the invention, the temperature increaser(91) increases the temperature of the power element (37) not when it isassumed that the dew condensation occurs in the power element (37) orthe surrounding component (16, 71) thereof, but when the dewcondensation actually occurs in the power element (37) or thesurrounding component (16, 71) thereof. This increases not only thetemperature of the power element (37) but also the temperature of thesurrounding component (16, 71) of the power element (37).

A twenty-seventh aspect of the invention is intended to therefrigeration apparatus of any one of the twentieth to twenty-sixthaspects of the invention, in which the temperature increaser (91)includes a heat generation amount increaser (56) increasing an amount ofheat generation of the power element (37).

In the twenty-seventh aspect of the invention, the heat generationamount increaser (56) increases the amount of heat generation of thepower element (37), thereby increasing the temperature of the powerelement (37).

A twenty-eighth aspect of the invention is intended to the refrigerationapparatus of any one of the twentieth to twenty-sixth aspects of theinvention, in which the temperature increaser (91) includes a heater(95) heating the power element (37).

In the twenty-eighth aspect of the invention, the heater (95) heats thepower element (37), thereby increasing the temperature of the powerelement (37).

A twenty-ninth aspect of the invention is intended to the refrigerationapparatus of the twenty-seventh aspect of the invention, which furtherincludes a heat generation amount resetter (57) configured to, when thedew condensation state is cleared, reset the amount of heat generationof the power element (37) increased by the heat generation amountincreaser (56) to a normal state before an increase in heat generationamount.

In the twenty-ninth aspect of the invention, when the heat generationamount increaser (56) increases the amount of heat generation of thepower element (37) and then the dew condensation state is cleared, theheat generation amount resetter (57) resets the amount of heatgeneration of the power element (37) to the normal state before theincrease in heat generation amount.

A thirtieth aspect of the invention is intended to the refrigerationapparatus of the twenty-ninth aspect of the invention, which furtherincludes a forcible heat generation amount resetter (58) configured to,after a predetermined time has lapsed since the amount of heatgeneration of the power element (37) is increased by the heat generationamount increaser (56), forcibly reset the amount of heat generation ofthe power element (37) increased by the heat generation amount increaser(56) to the normal state before the increase in heat generation amount.

The power element (37) generates high-temperature heat, and tends to bebroken down when the temperature thereof is increased beyond a limittemperature. For such a reason, it is not preferable consideringprotection of the power element (37) that the state in which the amountof heat generation of the power element (37) is large continues for along period of time. When the dew condensation is highly likely tooccur, it is determined that the dew condensation state is established,and then the amount of heat generation of the power element (37) isincreased. Although the dew condensation state is actually cleared, itis determined that the dew condensation state is still established.Thus, there is a possibility that the state in which the amount of heatgeneration of the power element (37) is large continues uselessly.

Thus, in the thirtieth aspect of the invention, after the predeterminedtime has lapsed since the amount of heat generation of the power element(37) is increased, the amount of heat generation of the power element(37) is forcibly reset to the normal state before the increase in heatgeneration amount.

A thirty-first aspect of the invention is intended to the refrigerationapparatus of any one of the twenty-seventh, twenty-ninth, and thirtiesaspects of the invention, in which the heat generation amount increaser(56) increases a current value of the compressor (11) to increase theamount of heat generation of the power element (37) controlling thecompressor (11).

In the thirty-first aspect of the invention, power elements (37)controlling components together form a single power module under normalconditions. Thus, when the heat generation amount increaser (56)increases the amount of heat generation of the power element (37)controlling the compressor (11), the temperature of the entirety of thepower module is also increased.

A thirty-second aspect of the invention is intended to the refrigerationapparatus of any one of the twenty-seventh, twenty-ninth, and thirtiesaspects of the invention, in which the power element (37) is a switchingelement, and the heat generation amount increaser (56) increases aswitching frequency of the switching element to increase the amount ofheat generation of the power element (37).

In the thirty-second aspect of the invention, when the heat generationamount increaser (56) increases the switching frequency of the switchingelement, the amount of heat generation of the power element (37) isincreased, and then the temperature of the power element (37) and thesurrounding component (16, 71) thereof is increased.

A thirty-third aspect of the invention is intended to the refrigerationapparatus of any one of the twenty-seventh, twenty-ninth, and thirtiesaspects of the invention, in which the power element (37) is a switchingelement, and the heat generation amount increaser (56) increases a lossof the switching element to increase the amount of heat generation ofthe power element (37).

In the thirty-third aspect of the invention, when the heat generationamount increaser (56) increases the loss of the switching elementserving as the power element (37), the amount of heat generation of thepower element (37) is increased, and then the temperature of the powerelement (37) and the surrounding component (16, 71) thereof isincreased.

A thirty-fourth aspect of the invention is intended to the refrigerationapparatus of any one of the twenty-seventh, twenty-ninth, and thirtiesaspects of the invention, in which the heat generation amount increaser(56) increases a conduction loss of the power element (37) to increasethe amount of heat generation of the power element (37).

In the thirty-third aspect of the invention, when the heat generationamount increaser (56) increases the conduction loss of the power element(37), the amount of heat generation of the power element (37) isincreased, and then the temperature of the power element (37) and thesurrounding component (16, 71) thereof is increased.

Advantages of the Invention

According to the present invention, since the adjusting mechanism (90)is provided to adjust the temperature of refrigerant passing through thecooler (16), the temperature of the cooler (16) can be adjusted to asuitable temperature. That is, the temperature of refrigerant passingthrough the cooler (16) can be adjusted depending on the amount of heatgeneration of the power element (37) or the change in installationenvironment of the power element (37). Thus, insufficient cooling orexcessive cooling of the power element (37) by the cooler (16) can bereduced, thereby improving efficiency of cooling of the power element(37) by the cooler (16).

According to the second and third aspects of the invention, thetemperature of the cooler (16) can be adjusted to a suitable temperatureby a simple configuration. In addition, according to the third aspect ofthe invention, the moisturizing of refrigerant cooling the power element(37) and returning to the compressor (11) can be prevented. Thus, thebreakdown of the compressor (11) due to liquid refrigerant flowing intothe compressor (11) can be prevented.

According to the fourth aspect of the invention, since the amount ofrefrigerant larger than that in the normal operation can circulatethrough the branch circuit (10B) upon the start of the refrigerationapparatus, the unevenness in temperature of the cooler (16) can beprevented. In addition, after the start of the refrigeration apparatus,refrigerant can promptly reach the cooler (16). Thus, the power element(37) can be sufficiently cooled right after the start of therefrigeration apparatus.

According to the fifth aspect of the invention, the flow of refrigerantinto the cooler (16) after the stoppage of the refrigeration apparatuscan be reduced by providing the stop controller (97). This reduces thedecrease in temperature of the cooler (16). Thus, the occurrence of thedew condensation in the cooler (16) can be prevented, and the breakdownof the power element (37) due to the adherence of dew condensation watercan be prevented.

According to the sixth aspect of the invention, since the fixed throttle(4) is provided in parallel to the throttle mechanism (17) providedupstream of the cooler (16), the significantly-low evaporation pressureof refrigerant in the cooler (16) can be prevented upon the breakdown ofthe throttle mechanism (17). This prevents the excessive decrease intemperature of refrigerant circulating through the cooler (16) and theexcess of the cooling capacity of the cooler (16). In addition, thesignificantly-low flow rate of refrigerant flowing into the cooler (16)can be prevented upon the breakdown of the throttle mechanism (17). Thisprevents the deficiency of the cooling capacity of the cooler (16).

According to the seventh aspect of the invention, since the fixedthrottle (5) is provided in series with the throttle valve (18, 28), thesignificantly-low evaporation pressure of refrigerant in the cooler (16)can be prevented upon the breakdown of the throttle valve (18, 28). Thisprevents the excessive decrease in temperature of refrigerantcirculating through the cooler (16) and the excess of the coolingcapacity of the cooler (16). In addition, upon the breakdown of thethrottle valve (18, 28), the fixed throttle (5) can control the amountof refrigerant flowing out from the cooler (16) not to be significantlylarge. This prevents refrigerant branched from the main flow fromuselessly passing through the cooler (16) without the sufficient heatexchange with the power element (37).

According to the eighth aspect of the invention, when the detectionvalue of the detector (41, 46, 47, 48) indicates the dew condensationstate in which the dew condensation is highly likely to occur in thepower element (37) or the surrounding component (16, 71) thereof, theforcible opening degree reducer (55) forcibly reduces the degree ofopening of the throttle valve (18, 28). Thus, since the amount ofrefrigerant passing through the cooler (16) is reduced, and the amountof heat absorbed by refrigerant in the cooler (16) is reduced, theexcessive decrease in temperature of the power element (37) or thecooler (16) can be reduced. The occurrence of the dew condensation inthe power element (37) and the surrounding component (16, 71) thereofcan be reduced. In addition, corrosion of, e.g., metal componentsarranged near the power element (37) and the surrounding components (16,71) thereof and degradation of insulating performance of the powerelement (37) can be prevented.

According to the ninth to eleventh aspects of the invention, since thetemperature sensor (46) and the air temperature sensor (41) are used, itcan be easily detected with high accuracy that the dew condensation ishighly likely to occur in the power element (37) or the surroundingcomponents (16, 71) thereof. In addition, the occurrence of the dewcondensation can be prevented.

According to the tenth aspect of the invention, when the estimatedtemperature of the electrical connection part of the power element (37)where the short circuit may occur due to the adherence of dewcondensation water is lower than the air temperature, the degree ofopening of the throttle valve (18, 28) is forcibly reduced by theforcible opening degree reducer (55). Thus, the temperature ofrefrigerant in the cooler (16) can be reduced to the lowest possibletemperature at which the dew condensation does not occur in theelectrical connection part of the power element (37). Thus, thebreakdown of the power element (37) can be prevented, and performance ofthe cooler (16) can be improved.

According to the twelfth aspect of the invention, since the humiditysensor (47) is used, it can be easily detected with high accuracy thatthe dew condensation is highly likely to occur in the power element (37)or the surrounding components (16, 71) thereof. In addition, theoccurrence of the dew condensation can be prevented.

According to the thirteenth aspect of the invention, since the humiditysensor (48), the air temperature sensor (41), and the temperature sensor(46) are used, it can be easily detected with high accuracy that the dewcondensation is highly likely to occur in the power element (37) or thesurrounding components (16, 71) thereof. In addition, since the amountof heat generation of the power element (37) is increased when thepossibility of the occurrence of the dew condensation is increased, theoccurrence of the dew condensation can be prevented.

According to the fourteenth aspect of the invention, when the detectionvalue of the dew condensation sensor (45) indicates the dew condensationstate in which the dew condensation occurs in the power element (37) orthe surrounding component (16, 71) thereof, the forcible opening degreereducer (55) forcibly reduces the degree of opening of the throttlevalve (18, 28). Thus, since the amount of refrigerant passing throughthe cooler (16) is reduced, and the amount of heat absorbed byrefrigerant in the cooler (16) is reduced, the excessive decrease intemperature of the power element (37) or the cooler (16) can be reduced.The occurrence of the dew condensation in the power element (37) and thesurrounding component (16, 71) thereof can be reduced. In addition, thecorrosion of, e.g., the metal components arranged near the power element(37) and the surrounding components (16, 71) thereof and the degradationof the insulating performance of the power element (37) can beprevented.

According to the fifteenth and sixteenth aspects of the invention, theclosing unit (6) is provided. Thus, upon the power shutdown such as theblackout, the circulation of refrigeration through the cooler (16) canbe blocked, and the decrease in temperature of the cooler (16) can bereduced. Consequently, the occurrence of the dew condensation can beprevented, and the breakdown of the power element (37) due to theadherence of dew condensation water can be prevented.

According to the sixteenth aspect of the invention, the closing unit (6)can be easily configured.

According to the seventeenth aspect of the invention, the power shutdownadjusting unit (6 b) is provided. Thus, upon the power shutdown such asthe blackout, the circulation of refrigeration through the cooler (16)can be blocked, and the decrease in temperature of the cooler (16) canbe reduced. Consequently, the occurrence of the dew condensation can beprevented, and the breakdown of the power element (37) due to theadherence of dew condensation water can be prevented.

According to the eighteenth aspect of the invention, the pump-downcontroller (98) is provided, which is configured to perform thepump-down operation, estimate the overheating point bringing about theoverheating state of the power element (37) during the pump-downoperation, and complete the pump-down operation before the overheatingpoint. Thus, the breakdown of the power element (37) can be prevented,and it can be ensured that the pump-down operation is performed.

According to the nineteenth aspect of the invention, since the startinterrupting unit (99) interrupts the start of the refrigerationapparatus when the dew condensation is highly likely to occur in thecooler (16), the short circuit in, e.g., the electrical connection partof the power element (37) upon the start of the refrigeration apparatuscan be prevented. In other words, the start of the refrigerationapparatus is allowed only when there is no possibility that the shortcircuit is caused, thereby ensuring safety upon the start of therefrigeration apparatus.

According to the twentieth aspect of the invention, when the detectionvalue of the detector (41, 46, 47, 48) indicates the dew condensationstate in which the dew condensation is highly likely to occur in thepower element (37) or the surrounding component (16, 71) thereof, thetemperature increaser (91) increases the temperature of the powerelement (37) and the temperature of the surrounding component (16, 71)of the power element (37). This reduces the occurrence of the dewcondensation in the power element (37) and the surrounding component(16, 71) thereof. In addition, the corrosion of, e.g., the metalcomponents arranged near the power element (37) and the surroundingcomponents (16, 71) thereof and the degradation of the insulatingperformance of the power element (37) can be prevented.

According to the twenty-first to twenty-third aspects of the invention,since the temperature sensor (46) and the air temperature sensor (41)are used, it can be easily detected with high accuracy that the dewcondensation is highly likely to occur in the power element (37) or thesurrounding components (16, 71) thereof. In addition, the occurrence ofthe dew condensation can be prevented.

According to the twenty-second aspect of the invention, when there is nopossibility that the dew condensation occurs in the electricalconnection part of the power element (37) where the short circuit mayoccur due to the adherence of dew condensation water, the temperatureincreaser (91) can prevent the temperature of the power element (37)from being uselessly increased. Thus, the breakdown of the power element(37) can be prevented without uselessly increasing the amount of heatgeneration of the power element (37).

According to the twenty-fourth aspect of the invention, since thehumidity sensor (47) is used, it can be easily detected with highaccuracy that the dew condensation is highly likely to occur in thepower element (37) or the surrounding components (16, 71) thereof. Inaddition, the occurrence of the dew condensation can be prevented.

According to the twenty-fifth aspect of the invention, since thehumidity sensor (48), the air temperature sensor (41), and thetemperature sensor (46) are used, it can be easily detected with highaccuracy that the dew condensation is highly likely to occur in thepower element (37) or the surrounding components (16, 71) thereof. Inaddition, since the amount of heat generation of the power element (37)is increased when the possibility of the occurrence of the dewcondensation is increased, the occurrence of the dew condensation can beprevented.

According to the twenty-sixth aspect of the invention, when thedetection value of the dew condensation sensor (45) indicates the dewcondensation state in which the dew condensation occurs in the powerelement (37) or the surrounding component (16, 71) thereof, thetemperature increaser (91) increases the temperature of the powerelement (37) and the temperature of the surrounding component (16, 71)thereof. Thus, the occurrence of the dew condensation in the powerelement (37) and the surrounding component (16, 71) thereof can bereduced. In addition, the corrosion of, e.g., the metal componentsarranged near the power element (37) and the surrounding components (16,71) thereof and the degradation of the insulating performance of thepower element (37) can be prevented.

According to the twenty-seventh aspect of the invention, the amount ofheat generation of the power element (37) is increased withoutseparately using, e.g., a heating unit, thereby easily increasing thetemperature of the power element (37).

According to the twenty-eighth aspect of the invention, the temperatureof the power element (37) can be easily increased by using the heater(95).

According to the twenty-ninth aspect of the invention, the detector candetect with high accuracy that the dew condensation state is cleared. Assoon as the dew condensation state is cleared, the amount of heatgeneration of the power element (37) can be reset to the normal state.Thus, a heat loss caused due to the increase in amount of heatgeneration of the power element (37) can be suppressed to the minimum.

According to the thirtieth aspect of the invention, since the amount ofheat generation of the power element (37) is forcibly reset after thelapse of the predetermined time from the increase in amount of heatgeneration of the power element (37), the breakdown of the power element(37) can be prevented, and the heat loss of the power element (37) canbe reduced.

According to the thirty-first aspect of the invention, the current valueof the compressor (11) is increased to increase the amount of heatgeneration of the power element (37) controlling the compressor (11)without separately using, e.g., the heating unit. Thus, the temperatureof the entirety of the power module can be increased. Thus, theoccurrence of the dew condensation in the power element (37) or thesurrounding component (16, 71) thereof can be easily reduced.

According to the thirty-second to thirty-fourth aspects of theinvention, the amount of heat generation of the power element (37) iseasily increased without separately using, e.g., a heating unit, therebyreducing the occurrence of the dew condensation in the power element(37) or the surrounding component (16, 71) thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a piping diagram illustrating a configuration of arefrigeration apparatus of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a drive circuit of a power supplydevice of the first embodiment.

FIG. 3 is a cross-sectional view illustrating a vicinity of a powerelement(s) and a cooler of the first embodiment.

FIG. 4 is a flow chart illustrating a dew condensation reductionoperation control of the first embodiment.

FIG. 5 is a cross-sectional view illustrating a vicinity of a powerelement(s) and a cooler of a second embodiment.

FIG. 6 is a flow chart illustrating a dew condensation reductionoperation control of the second embodiment.

FIG. 7 is a flow chart illustrating a dew condensation reductionoperation control of a third embodiment.

FIG. 8 is a flow chart illustrating a dew condensation reductionoperation control of a fourth embodiment.

FIG. 9 is a cross-sectional view illustrating a vicinity of a powerelement(s) and a cooler of a fifth embodiment.

FIG. 10 is a flow chart illustrating a dew condensation reductionoperation control of the fifth embodiment.

FIG. 11 is a cross-sectional view illustrating a vicinity of a powerelement(s) and a cooler of a sixth embodiment.

FIG. 12 is a flow chart illustrating a dew condensation reductionoperation control of the sixth embodiment.

FIG. 13 is a piping diagram illustrating a configuration of arefrigeration apparatus of a seventh embodiment.

FIG. 14 is a flow chart illustrating a dew condensation reductionoperation control of the seventh embodiment.

FIG. 15 is a flow chart illustrating a dew condensation reductionoperation control of an eighth embodiment.

FIG. 16 is a flow chart illustrating a dew condensation reductionoperation control of a ninth embodiment.

FIG. 17 is a flow chart illustrating a dew condensation reductionoperation control of a tenth embodiment.

FIG. 18 is a flow chart illustrating a dew condensation reductionoperation control of an eleventh embodiment.

FIG. 19 is a flow chart illustrating a dew condensation reductionoperation control of a twelfth embodiment.

FIG. 20( a) illustrates an ON/OFF control of a switching element in anormal operation control of a thirteenth embodiment over time. FIG. 20(b) illustrates an ON/OFF control of a switching element in a dewcondensation reduction operation control of the thirteenth embodimentover time.

FIGS. 21( a) and 21(c) respectively illustrate examples of a basecircuit of a power supply device of a fourteenth embodiment. FIG. 21( b)is a graph illustrating base voltage in a normal operation and a dewcondensation reduction operation of the fourteenth embodiment over time.

FIG. 22 is a graph illustrating, in a first example of a fifteenthembodiment where a conduction loss of a power element is increased, arelationship between a current phase input from a drive circuit to adriver and the conduction loss of the power element.

FIG. 23 is a graph illustrating, in a second example of the fifteenthembodiment where a conduction loss of a power element is increased, acomparison of emitter-collector voltage between a normal operationcontrol and a dew condensation reduction operation control.

FIG. 24 illustrates, in the second example of the fifteenth embodimentwhere the conduction loss of the power element is increased, an exampleof a drive circuit configured to fluctuate the emitter-collectorvoltage.

FIG. 25 is a piping diagram illustrating a configuration of arefrigeration apparatus of a sixteenth embodiment.

FIG. 26 is a piping diagram illustrating a configuration of arefrigeration apparatus of a seventeenth embodiment.

FIG. 27 is a piping diagram illustrating a configuration of arefrigeration apparatus of an eighteenth embodiment.

FIG. 28 is a piping diagram illustrating a configuration of arefrigeration apparatus of a nineteenth embodiment.

FIG. 29 is a piping diagram illustrating a configuration of arefrigeration apparatus of a twentieth embodiment.

FIG. 30 is a piping diagram illustrating another configuration of therefrigeration apparatus of the twentieth embodiment.

FIG. 31 is a piping diagram illustrating a configuration of arefrigeration apparatus of a twenty-second embodiment.

FIG. 32 is a piping diagram illustrating a configuration of arefrigeration apparatus of a twenty-third embodiment.

FIG. 33 is a piping diagram illustrating a configuration of arefrigeration apparatus of a twenty-fourth embodiment.

FIG. 34 is a piping diagram illustrating a configuration of arefrigeration apparatus of a twenty-fifth embodiment.

FIG. 35 is a piping diagram illustrating a configuration of arefrigeration apparatus of a twenty-sixth embodiment.

FIG. 36 is a piping diagram illustrating a configuration of arefrigeration apparatus of a twenty-seventh embodiment.

FIG. 37 is a piping diagram illustrating a configuration of arefrigeration apparatus of a twenty-eighth embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below in detailwith reference to drawings.

First Embodiment of the Invention Entire Configuration

As illustrated in FIG. 1, a refrigeration apparatus (1) of an embodimentof the present invention includes a heat-source-side unit (1A) and autilization-side unit (1B), and further includes a refrigerant circuit(10) configured to perform a vapor compression refrigeration cycle. Therefrigeration apparatus of the present invention may be, e.g., an airconditioning apparatus or a cooling apparatus configured to cool aninside of a refrigerator or a freezer. In the present embodiment, an airconditioning apparatus configured to cool air inside a room will bedescribed as an example.

The refrigerant circuit (10) includes a main circuit (10A) in which acompressor (11), a heat-source-side heat exchanger (12), an expansionvalve (13), and a utilization-side heat exchanger (14) are connectedtogether in this order through refrigerant pipes. Note that, in a firstembodiment, the main circuit (10A) is configured such that refrigerantcirculates in one direction and do not circulate in an oppositedirection. Thus, in the present embodiment, the heat-source-side heatexchanger (12) functions as a condenser on every occasion, and theutilization-side heat exchanger (14) functions as an evaporator on everyoccasion. In the first embodiment, each of the heat-source-side heatexchanger (12) and the utilization-side heat exchanger (14) is across-fin type fin-and-tube heat exchanger, and is configured toexchange heat between refrigerant of the main circuit (10A) and air.

The compressor (11) includes a motor (11 a) rotatably driven by a powersupply device (30) which will be described later. Although the detailswill be described later, the motor (11 a) is configured such that therotational speed thereof is adjustable by the power supply device (30).An accumulator (15) configured to remove liquid refrigerant contained inrefrigerant and supply only gas refrigerant to the compressor (11) isprovided on an inlet side of the compressor (11).

The refrigerant circuit (10) further includes a branch circuit (10B)branched from part of the main circuit (10A) between theheat-source-side heat exchanger (12) and the expansion valve (13). Anoutlet end of the branch circuit (10B) is connected to the compressor(11). Note that, in the first embodiment, the outlet end of the branchcircuit (10B) is connected to an intermediate port of the compressor(11) communicating with a compression chamber in the middle ofcompression.

In the branch circuit (10B), a cooler (16) configured to cool a powerelement(s) (37) which will be described later is provided. A firstthrottle valve (18) and a second throttle valve (17), the degree ofopening of each of which is variable, are provided downstream andupstream of the cooler (16) of the branch circuit (10B), respectively.

A heat-source-side fan (12 a) is provided near the heat-source-side heatexchanger (12), and a utilization-side fan (14 a) is provided near theutilization-side heat exchanger (14). The compressor (11), theheat-source-side heat exchanger (12), the heat-source-side fan (12 a),the expansion valve (13), and the branch circuit (10B) are provided inthe heat-source-side unit (1A). The utilization-side heat exchanger (14)and the utilization-side fan (14 a) are provided in the utilization-sideunit (1B).

<Power Supply Device>

The power supply device (30) configured to supply power to each ofdrivers of components of the refrigerant circuit (10) is provided in theheat-source-side unit (1A).

As illustrated in FIG. 2, the power supply device (30) includes a drivecircuit (31) configured to control and convert power supplied to thedrivers such as the motor (11 a) of the compressor (11). Note that, asan example of the drive circuit (31), FIG. 2 illustrates the drivecircuit (31) for the compressor (11), which is connected to the motor(11 a) of the compressor (11). The drive circuit (31) includes arectifier circuit (32) connected to a commercial power source (38), acapacitor circuit (33), and an inverter circuit (34) connected to themotor (11 a) of the compressor (11), i.e., the driver of the compressor(11).

The rectifier circuit (32) is connected to the commercial power source(38) which is a three-phase AC power source. The rectifier circuit (32)is a circuit configured to convert AC voltage of the commercial powersource (38) into DC voltage, and six diodes (35) are connected togetherin a three-phase bridge configuration.

The capacitor circuit (33) is connected between the rectifier circuit(32) and the inverter circuit (34), and includes a capacitor (36).

The inverter circuit (34) is configured to convert DC voltage of thecapacitor circuit (33) into three-phase AC voltage and supply theconverted AC voltage to the motor (11 a) which is a load. In theinverter circuit (34), six switching elements are connected together ina three-phase bridge configuration. Note that the switching element isthe power element (37) of the present invention, and, e.g., an insulatedgate bipolar transistor (IGBT) or a MOS field effect transistor(MOS-FET) is used as the switching element. In the inverter circuit(34), switching of the switching element(s) is controlled toincrease/decrease AC voltage output to the motor (11 a) and thefrequency of the AC voltage, thereby adjusting the rotational speed ofthe motor (11 a). Note that the switching of the switching element(s) iscontrolled by a control device (60).

According to the foregoing configuration, in the power supply device(30), after AC voltage of the commercial power source (38) is convertedinto DC voltage in the rectifier circuit (32), and the DC voltage isconverted into AC voltage having a desired frequency in the invertercircuit (34), the AC voltage is supplied to the drivers such as themotor (11 a) of the compressor (11).

As illustrated in FIG. 3, in the present embodiment, the power elements(37) of the drive circuits (31) for the compressor (11) and the othercomponents together form a single power module (61). The power module(61) and other electric components (not shown in the figure) are mountedon a substrate (71) provided in the heat-source-side unit (1A).

<Cooler>

The power element(s) (37) generates high-temperature heat when therefrigeration apparatus (1) is started. Thus, the cooler (16) configuredto cool the power element(s) (37) by refrigerant flowing through therefrigerant circuit (10) is provided. As described above, in the presentembodiment, the power elements (37) for the components together form thesingle power module (61). Thus, as illustrated in FIG. 3, the cooler(16) is provided so as to cool the power module (61).

The cooler (16) is made of, e.g., metal such as aluminum in a flatrectangular parallelepiped shape, and a refrigerant flow path throughwhich refrigerant circulates is formed inside the cooler (16). Therefrigerant flow path may be formed by inserting part of the refrigerantpipe or may be formed by connecting the refrigerant pipe to a tubularthrough-hole. In the present embodiment, the refrigerant flow path isformed by part of the branch circuit (10B) of the refrigerant circuit(10) inserted into the cooler (16) (see FIG. 1).

According to the foregoing configuration, the cooler (16) is configuredsuch that refrigerant flowing through the refrigerant circuit (10) cancirculate through the cooler (16). In addition, since the cooler (16) ismade of the metal such as aluminum, cold heat of refrigerant circulatingthrough the cooler (16) is transferred to an outer surface of the cooler(16).

<Detector>

As illustrated in FIG. 1, in the heat-source-side unit (1A), an outdoorair temperature sensor (41) configured to detect an outdoor airtemperature (air temperature before air passes through theheat-source-side heat exchanger (12)) is provided. On the other hand, inthe utilization-side unit (1B), a room temperature sensor (42)configured to detect a room temperature (air temperature before airpasses through the utilization-side heat exchanger (14)) is provided.

In the cooler (16), an evaporation temperature sensor (43) configured todetect the evaporation temperature of refrigerant in the cooler (16) isprovided. An outlet temperature sensor (44) configured to detect arefrigerant temperature at an outlet of the cooler (16) is provideddownstream of the cooler (16) in the branch circuit (10B).

As illustrated in FIG. 3, a dew condensation sensor (45) configured todetect dew condensation in the cooler (16) is provided in the cooler(16). The dew condensation sensor (45) is attached to a surface of thecooler (16) facing the power module (61).

The outdoor air temperature sensor (41), the room temperature sensor(42), the evaporation temperature sensor (43), the outlet temperaturesensor (44), and the dew condensation sensor (45) are connected to anoperation control device (50) which will be described later, andtransmit detection signals to the operation control device (50).

<Operation Control Device>

In the heat-source-side unit (1A), the operation control device (50)configured to control the drivers of the components of the refrigerantcircuit (10) is provided. The operation control device (50) is connectedto the control device (60) connected to each of the drive circuits (31),and is configured to transmit a control signal for controlling each ofthe drive circuits (31).

The control device (60) controls the switching of the switchingelement(s) serving as the power element(s) (37) based on the controlsignal from the operation control device (50), thereby controlling ACvoltage supplied to each of the drivers and the frequency of the ACvoltage. Specifically, the operation control device (50) transmitscontrol signals to the control devices (60) based on detection valuesof, e.g., the outdoor air temperature sensor (41) and the roomtemperature sensor (42) such that each of the drivers is in a desiredstate (e.g., the motor (11 a) has a desired rotational speed). Thecontrol device (60) converts the control signal into a drive signal, andoutputs the drive signal to the drive circuit (31) of the driver. Thedrive signal is input to a base circuit (not shown in the figure) ofeach of the switching elements, and ON/OFF of each of the switchingelements is controlled. This controls AC voltage supplied to each of thedrivers to desired voltage and frequency, and, e.g., the rotationalspeed of the motor (11 a) is changed to a desired rotational speed.

The operation control device (50) includes a normal operator (51)configured to perform a normal operation by adjusting the temperatureand the degree of superheating of refrigerant passing through the cooler(16), a dew condensation determinator (54), and a forcible openingdegree reducer (55). The dew condensation determinator (54) and theforcible opening degree reducer (55) are configured to perform a dewcondensation reduction operation which will be described later. Thenormal operator (51) includes a first opening degree adjuster (52)configured to adjust the degree of opening of the first throttle valve(18), and a second opening degree adjuster (53) configured to adjust thedegree of opening of the second throttle valve (17).

The first opening degree adjuster (52) adjusts the degree of opening ofthe first throttle valve (18) such that the evaporation temperature ofrefrigerant in the cooler (16) reaches a target temperature.Specifically, the first opening degree adjuster (52) reduces the degreeof opening of the first throttle valve (18) when a detection value ofthe evaporation temperature sensor (43) is lower than the targettemperature, and increases the degree of opening of the first throttlevalve (18) when the detection value of the evaporation temperaturesensor (43) is higher than the target temperature.

The second opening degree adjuster (53) adjusts the degree of opening ofthe second throttle valve (17) such that the degree of superheating ofrefrigerant at the outlet of the cooler (16) reaches a target degree ofsuperheating. Specifically, the second opening degree adjuster (53)reduces the degree of opening of the second throttle valve (17) when avalue obtained by subtracting a detection value of the evaporationtemperature sensor (43) from a detection value of the outlet temperaturesensor (44) (i.e., the degree of superheating of refrigerant at theoutlet of the cooler (16)) is smaller than the target degree ofsuperheating. The second opening degree adjuster (53) increases thedegree of opening of the second throttle valve (17) when the foregoingvalue is larger than the target degree of superheating.

The dew condensation determinator (54) refers to a detection value (dewcondensation signal) of the dew condensation sensor (45), and determinesbased on the detection value whether or not a dew condensation state inwhich the dew condensation occurs in the cooler (16) is established.

When the dew condensation determinator (54) determines that the dewcondensation state is established, the forcible opening degree reducer(55) forcibly reduces the degree of opening of the first throttle valve(18) on behalf of the first opening degree adjuster (52).

In the first embodiment, the first throttle valve (18), the secondthrottle valve (17), the first opening degree adjuster (52), and thesecond opening degree adjuster (53) form an adjusting mechanism (90) ofthe present invention. Note that the adjusting mechanism (90) of thepresent invention does not necessarily include the second opening degreeadjuster (53).

Operation

In the main circuit (10A) of the refrigerant circuit (10), when thecompressor (11) is driven, refrigerant circulates in a directionindicated by arrows of FIG. 1, thereby performing the vapor compressionrefrigeration cycle in which the heat-source-side heat exchanger (12)functions as the condenser and the utilization-side heat exchanger (14)functions as the evaporator. In the utilization-side heat exchanger(14), refrigerant flowing through the utilization-side heat exchanger(14) functioning as the evaporator absorbs heat from air taken by theutilization-side fan (14 a), and the air is cooled. The cooled air isdischarged to a room or a container by the utilization-side fan (14 a)to cool an inside of the room or the container.

<Cooling of Power Element>

When the compressor (11) is driven, part of high-pressure liquidrefrigerant condensed in the heat-source-side heat exchanger (12) of themain circuit (10A) is branched and flows into the branch circuit (10B)of the refrigerant circuit (10). The high-pressure liquid refrigerantflowing into the branch circuit (10B) passes through the first throttlevalve (18), and then flows into the cooler (16). In the cooler (16), thepower module (61) formed by the plurality of power elements (37) iscooled by dissipating heat to the refrigerant flowing through the cooler(16).

<Control by Control Device>

The operation control device (50) configured to control power suppliedto the drivers of the components of the refrigerant circuit (10)performs a normal operation control and a dew condensation reductionoperation control as described below.

<<Normal Operation Control>>

The operation control device (50) controls the components of therefrigerant circuit (10) based on detection values of the roomtemperature sensor (42) and the outdoor air temperature sensor (41) suchthat a room temperature reaches a desired temperature. For, e.g., themotor (11 a) of the compressor (11), the operation control device (50)increases the rotational speed of the motor (11 a) of the compressor(11) when the room temperature is higher than the desired temperature,and decreases the rotational speed of the motor (11 a) of the compressor(11) when the room temperature is lower than the desired temperature.

The normal operator (51) of the operation control device (50) adjuststhe temperature and the degree of superheating of refrigerant passingthrough the cooler (16). Specifically, the first opening degree adjuster(52) adjusts the degree of opening of the first throttle valve (18) suchthat the evaporation temperature of refrigerant in the cooler (16)reaches the target temperature. In addition, the second opening degreeadjuster (53) adjusts the degree of opening of the second throttle valve(17) such that the degree of superheating of refrigerant at the outletof the cooler (16) reaches the target degree of superheating. Morespecifically, the first opening degree adjuster (52) reduces the degreeof opening of the first throttle valve (18) when the evaporationtemperature of refrigerant in the cooler (16) is lower than the targettemperature, and increases the degree of opening of the first throttlevalve (18) when the evaporation temperature of refrigerant in the cooler(16) is higher than the target temperature. In addition, the secondopening degree adjuster (53) reduces the degree of opening of the secondthrottle valve (17) when the degree of superheating of refrigerant atthe outlet of the cooler (16) is smaller than the target degree ofsuperheating, and increases the degree of opening of the second throttlevalve (17) when the degree of superheating of refrigerant at the outletof the cooler (16) is larger than the target degree of superheating.Thus, the temperature of refrigerant passing through the cooler (16) canbe the target temperature, and moisturizing of refrigerant to beintroduced into the compressor (11) can be prevented.

<<Dew Condensation Reduction Operation Control>>

As described above, depending on operation conditions or outdoor airconditions, the temperatures of the cooler (16) and surroundingcomponents thereof (e.g., the power module (61) and the substrate (71))may fall below the dew-point temperature of surrounding air, andtherefore the dew condensation may occur in the cooler (16) and thesurrounding components thereof. Thus, in parallel with the normaloperation control, the dew condensation reduction operation controlwhich will be described below is performed at predetermined timeintervals (e.g., at intervals of 30 seconds).

As illustrated in FIG. 4, the dew condensation determinator (54) firstrefers to a dew condensation signal from the dew condensation sensor(45) (step S11), and then determines whether or not the dew condensationstate in which the dew condensation occurs in the cooler (16) isestablished (step S12). If the dew condensation determinator (54)determines that the dew condensation state is established, the forcibleopening degree reducer (55) forcibly reduces the degree of opening ofthe first throttle valve (first adjusting valve) (18) by a predeterminedvalue on behalf of the first opening degree adjuster (52) (step S13).

When the degree of opening of the first throttle valve (18) is forciblyreduced, the amount of refrigerant flowing into the branch circuit (10B)is reduced, and therefore the amount of heat absorbed by refrigerant inthe cooler (16) (the amount of heat dissipated from the power module(61)) is reduced. Thus, the dew condensation in the power module (61)and the surrounding components thereof is reduced, and the dewcondensation state in the cooler (16) is cleared.

After the degree of opening of the first throttle valve (18) is forciblyreduced by the forcible opening degree reducer (55) as described above,the process returns to step S11, and the operation control device (50)repeats the same process. As a result, while the dew condensationdeterminator (54) determines that the dew condensation state isestablished, the degree of opening of the first throttle valve (18) isreduced by the forcible opening degree reducer (55) every time the dewcondensation reduction operation control is performed. When the dewcondensation determinator (54) no longer determines that the dewcondensation state is established, the operation control device (50)resumes the normal operation control, and adjusts the degree of openingof the first throttle valve (18) such that the evaporation temperatureof refrigerant in the cooler (16) reaches the target temperature.

Advantages of First Embodiment

As described above, according to the first embodiment, since theadjusting mechanism (90) is provided to adjust the temperature ofrefrigerant passing through the cooler (16), the temperature of thecooler (16) can be adjusted to a suitable temperature. That is, thetemperature of refrigerant passing through the cooler (16) can beadjusted depending on the amount of heat generation of the powerelement(s) (37) or a change in installation environment of the powerelement(s) (37). Thus, insufficient cooling or excessive cooling of thepower element(s) (37) by the cooler (16) can be reduced, therebyimproving efficiency of cooling of the power element(s) (37) by thecooler (16).

According to the first embodiment, since the first opening degreeadjuster (52) configured to adjust the degree of opening of the firstthrottle valve (18) such that the evaporation temperature of refrigerantin the cooler (16) reaches the target temperature is provided, thetemperature of the cooler (16) can be adjusted to a suitable temperatureby a simple configuration.

According to the first embodiment, since the second opening degreeadjuster (53) configured to adjust the degree of opening of the secondthrottle valve (17) such that the degree of superheating of refrigerantat the outlet of the cooler (16) reaches the target degree ofsuperheating is provided, the moisturizing of refrigerant cooling thepower element(s) (37) and returning to the compressor (11) can beprevented. Thus, a breakdown of the compressor (11) due to liquidrefrigerant flowing into the compressor (11) can be prevented.

According to the first embodiment, since the dew condensationdeterminator (54) and the forcible opening degree reducer (55) areprovided, the degree of opening of the first throttle valve (18) isforcibly reduced by the forcible opening degree reducer (55) when thedew condensation determinator (54) determines that the dew condensationstate is established. As a result, the amount of refrigerant flowinginto the cooler (16) is reduced, and the amount of heat absorbed byrefrigerant in the cooler (16) is reduced. Thus, an excessive decreasein temperature of the power element(s) (37) or the cooler (16) can bereduced. Consequently, the occurrence of the dew condensation in thepower element(s) (37) and the surrounding components (16, 71) thereofcan be reduced, and corrosion of, e.g., metal components arranged nearthe power element(s) (37) and the surrounding components (16, 71)thereof and degradation of insulating performance of the powerelement(s) (37) can be prevented.

According to the first embodiment, since the dew condensation sensor(45) is used, the occurrence of the dew condensation can be easilydetected with high accuracy.

Under normal conditions, the cooler (16) configured to cool the powerelement(s) (37) has a temperature lower than that of the powerelement(s) (37) during the operation of the refrigeration apparatus (1).Thus, it is likely that the dew condensation occurs in the cooler (16)before the dew condensation occurs in the power element(s) (37).

In the present embodiment, since the dew condensation sensor (45) isattached to the cooler (16), the occurrence of the dew condensation canbe detected at a relatively early stage. Thus, e.g., when the dewcondensation occurs in the cooler (16) and does not occur in the powerelement(s) (37), the degree of opening of the first throttle valve (18)is reduced to prevent the dew condensation from occurring in the powerelement(s) (37).

The dew condensation sensor (45) may be attached to the power element(s)(37) (in the present embodiment, the power module (61)) or thesurrounding components (e.g., the substrate (71)) thereof.

Second Embodiment of the Invention

As illustrated in FIG. 5, in a refrigeration apparatus (1) of a secondembodiment, a temperature sensor (46) is provided near a powerelement(s) (37) instead of providing the dew condensation sensor (45) ofthe first embodiment. In addition, an outdoor air temperature sensor(41) is used as an air temperature sensor of the present inventionconfigured to detect an air temperature around a power supply device(30). In the refrigeration apparatus (1) of the second embodiment, thetemperature sensor (46) and the outdoor air temperature sensor (41) areused as detectors each configured to detect a physical amount based onwhich it is determined whether or not a dew condensation state isestablished.

The temperature sensor (46) is attached to a surface of a cooler (16)facing a power module (61). The temperature sensor (46) is connected toan operation control device (50), and transmits a detection signal tothe operation control device (50). When a detection value of thetemperature sensor (46) is lower than a detection value of the outdoorair temperature sensor (41), a dew condensation determinator (54) of theoperation control device (50) determines that the dew condensation statein which dew condensation is highly likely to occur in the powerelement(s) (37) and surrounding components (16, 71) thereof isestablished. Since other configurations of the present embodiment aresimilar to those of the first embodiment, the description thereof willnot be repeated.

A refrigeration cycle, cooling of the power element(s), and a normaloperation control by the operation control device (50) in the presentembodiment are similar to those of the first embodiment. A dewcondensation reduction operation control by the operation control device(50) will be described below.

As illustrated in FIG. 6, the dew condensation determinator (54) firstrefers to a detection value (outdoor air temperature) Ta of the outdoorair temperature sensor (41) (step S21), and then refers to a detectionvalue (temperature of the cooler (16)) Td of the temperature sensor (46)(step S22).

Next, the dew condensation determinator (54) determines whether or notthe dew condensation state in which the dew condensation is highlylikely to occur in the cooler (16) is established (step S23). Note that,when the detection value Td of the temperature sensor (46) is lower thanthe detection value Ta of the outdoor air temperature sensor (41), thedew condensation determinator (54) determines that the dew condensationstate is established.

When the dew condensation determinator (54) determines at step S23 thatthe dew condensation state is established, a forcible opening degreereducer (55) forcibly reduces the degree of opening of a first throttlevalve (18) by a predetermined value on behalf of a first opening degreeadjuster (52) (step S24).

When the degree of opening of the first throttle valve (18) is forciblyreduced, the amount of refrigerant flowing into a branch circuit (10B)is reduced, and therefore the amount of heat absorbed by refrigerant inthe cooler (16) (the amount of heat dissipated from the power module(61)) is reduced. Thus, the dew condensation in the power module (61)and the surrounding components (16, 71) thereof is reduced, and the dewcondensation state in the cooler (16) is cleared.

After the degree of opening of the first throttle valve (18) is forciblyreduced by the forcible opening degree reducer (55) as described above,the process returns to step S21, and the operation control device (50)repeats the same process. As a result, while the dew condensationdeterminator (54) determines that the dew condensation state isestablished, the degree of opening of the first throttle valve (18) isreduced by the forcible opening degree reducer (55) every time the dewcondensation reduction operation control is performed. When the dewcondensation determinator (54) no longer determines that the dewcondensation state is established, the operation control device (50)resumes the normal operation control, and adjusts the degree of openingof the first throttle valve (18) such that the evaporation temperatureof refrigerant in the cooler (16) reaches a target temperature.

Advantages of Second Embodiment

In the second embodiment, since the state of air (state of outdoor air)before the air passes through a heat-source-side heat exchanger (12) andthe state of air around the power supply device (30) are substantiallythe same, the outdoor air temperature sensor (41) is used as the airtemperature sensor of the present invention. The temperature sensor (46)provided on the cooler (16) near the power element(s) (37) and theoutdoor air temperature sensor (41) are used as the detectors.

Since it is practically impossible that the relative humidity of outdoorair (relative humidity of air around the power supply device (30))reaches 100%, the dew-point temperature of outdoor air (dew-pointtemperature of air around the power supply device (30)) is lower thanthe temperature of outdoor air (dry-bulb temperature of air around thepower supply device (30)). In the state in which the detection value Tdof the temperature sensor (46) is lower than the detection value Ta ofthe outdoor air temperature sensor (41), the surface temperature of thecooler (16) is close to the dew-point temperature of outdoor air(dew-point temperature of air around the power supply device (30)).Thus, it can be assumed that the dew condensation is highly likely tooccur in the power element(s) (37) and the cooler (16).

When the detection value Td of the temperature sensor (46) is lower thanthe detection value Ta of the outdoor air temperature sensor (41), thedew condensation determinator (54) determines that the dew condensationstate is established.

Thus, according to the second embodiment, since the temperature sensor(46) and the outdoor air temperature sensor (41) are used, it can beeasily detected with high accuracy that the dew condensation is highlylikely to occur in the power element(s) (37) or the surroundingcomponents (16, 71) thereof. In addition, since the amount of heatgeneration of the power element(s) (37) is increased when thepossibility of the occurrence of the dew condensation is increased, theoccurrence of the dew condensation can be prevented.

Under normal conditions, the cooler (16) configured to cool the powerelement(s) (37) has a temperature lower than that of the powerelement(s) (37) during the operation of the refrigeration apparatus (1).Since the temperature sensor (46) is attached to the cooler (16), thepossibility of the occurrence of the dew condensation can be detected ata relatively early stage. Thus, it can be further ensured that theoccurrence of the dew condensation in the power element(s) (37) and thesurrounding components (16, 71) thereof is prevented.

Note that the temperature sensor (46) may be attached to the powerelement(s) (37) (in the present embodiment, the power module (61)) orthe surrounding components (e.g., the substrate (71)) thereof.

In the second embodiment, the outdoor air temperature sensor (41) isused as the air temperature sensor of the present invention. However,the air temperature sensor of the present invention may be any sensorsother than the outdoor air temperature sensor (41) as long as thetemperature of air around the power supply device (30) is detectable,and may be a sensor configured to detect the temperature of air aroundthe power supply device (30) in a heat-source-side unit (1A).

Third Embodiment of the Invention

A refrigeration apparatus (1) of a third embodiment is configuredsimilar to that of the second embodiment, except that a method fordetermining occurrence of dew condensation by a dew condensationdeterminator (54) of an operation control device (50) is different.Since other configurations and operations of the present embodiment aresimilar to those of the second embodiment, a dew condensation reductionoperation control by the operation control device (50) which isdifferent from that of the second embodiment will be described below.

As illustrated in FIG. 7, the dew condensation determinator (54) firstrefers to a detection value (outdoor air temperature) Ta of an outdoorair temperature sensor (41) (step S31). Next, based on the detectionvalue Ta of the outdoor air temperature sensor (41), the dewcondensation determinator (54) calculates a dew-point temperature Twwhen an air temperature is Ta and a relative humidity is H1 (step S32).Then, the dew condensation determinator (54) refers to a detection value(temperature Td of a cooler (16)) of a temperature sensor (46) (stepS33).

Subsequently, the dew condensation determinator (54) determines whetheror not a dew condensation state in which the dew condensation is highlylikely to occur in the cooler (16) is established (step S34). Note that,when the detection value Td of the temperature sensor (46) is lower thanthe dew-point temperature Tw, the dew condensation determinator (54)determines that the dew condensation state is established.

If the dew condensation determinator (54) determines that the dewcondensation state is established, a forcible opening degree reducer(55) forcibly reduces the degree of opening of a first throttle valve(18) by a predetermined value on behalf of a first opening degreeadjuster (52) (step S35).

When the degree of opening of the first throttle valve (18) is forciblyreduced, the amount of refrigerant flowing into a branch circuit (10B)is reduced, and therefore the amount of heat absorbed by refrigerant inthe cooler (16) (the amount of heat dissipated from a power module (61))is reduced. Thus, the dew condensation in the power module (61) andsurrounding components (16, 71) thereof is reduced, and the dewcondensation state in the cooler (16) is cleared.

After the degree of opening of the first throttle valve (18) is forciblyreduced by the forcible opening degree reducer (55) as described above,the process returns to step S31, and the operation control device (50)repeats the same process. As a result, while the dew condensationdeterminator (54) determines that the dew condensation state isestablished, the degree of opening of the first throttle valve (18) isreduced by the forcible opening degree reducer (55) every time the dewcondensation reduction operation control is performed. When the dewcondensation determinator (54) no longer determines that the dewcondensation state is established, the operation control device (50)resumes a normal operation control, and adjusts the degree of opening ofthe first throttle valve (18) such that the evaporation temperature ofrefrigerant in the cooler (16) reaches a target temperature.

Advantages of Third Embodiment

In the third embodiment, since the state of air (state of outdoor air)before the air passes through a heat-source-side heat exchanger (12) andthe state of air around a power supply device (30) are substantially thesame, the outdoor air temperature sensor (41) is used as the airtemperature sensor of the present invention. The temperature sensor (46)provided on the cooler (16) near power element(s) (37) and the outdoorair temperature sensor (41) are used as detectors.

Although the relative humidity of outdoor air (relative humidity of airaround the power supply device (30)) varies depending on, e.g.,installation environment, seasons, and time, the relative humidity canbe estimated considering, e.g., the installation environment and theusage time. In the third embodiment, the dew condensation determinator(54) estimates the dew-point temperature Tw of air outside aheat-source-side unit (1A) based on the detection value Ta of theoutdoor air temperature sensor (41) and the preset relative humidity H1(e.g., 60%), and, when the detection value Td of the temperature sensor(46) is lower than the dew-point temperature Tw, determines that the dewcondensation state is established.

As described above, according to the third embodiment, since thetemperature sensor (46) and the outdoor air temperature sensor (41) areused, it can be easily detected with high accuracy that the dewcondensation is highly likely to occur in the power element(s) (37) orthe surrounding components (16, 71) thereof. In addition, when thepossibility of the occurrence of the dew condensation is increased, thedegree of opening of the first throttle valve (18) is reduced, therebyreducing a decrease in temperature of the cooler (16). Thus, theoccurrence of the dew condensation can be prevented.

Under normal conditions, the cooler (16) configured to cool the powerelement(s) (37) has a temperature lower than that of the powerelement(s) (37) during the operation of the refrigeration apparatus (1).Since the temperature sensor (46) is attached to the cooler (16), thepossibility of the occurrence of the dew condensation can be detected ata relatively early stage. Thus, it can be further ensured that theoccurrence of the dew condensation in the power element(s) (37) and thesurrounding components (16, 71) thereof is prevented.

Note that the temperature sensor (46) may be attached to the powerelement(s) (37) (in the present embodiment, the power module (61)) orthe surrounding components (e.g., the substrate (71)) thereof.

In the third embodiment, the outdoor air temperature sensor (41) is usedas the air temperature sensor of the present invention. However, the airtemperature sensor of the present invention may be any sensors otherthan the outdoor air temperature sensor (41) as long as the temperatureof air around the power supply device (30) is detectable, and may be asensor configured to detect the temperature of air around the powersupply device (30) in the heat-source-side unit (1A).

Fourth Embodiment of the Invention

A refrigeration apparatus (1) of a fourth embodiment is configuredsimilar to that of the second embodiment, except that a method fordetermining occurrence of dew condensation by a dew condensationdeterminator (54) of an operation control device (50) is different.Since other configurations and operations of the present embodiment aresimilar to those of the second embodiment, a dew condensation reductionoperation control by the operation control device (50) which isdifferent from that of the second embodiment will be described below.

As illustrated in FIG. 8, the dew condensation determinator (54) firstrefers to a detection value (temperature Td of a cooler (16)) of atemperature sensor (46) (step S36). Next, the dew condensationdeterminator (54) calculates a temperature (Td+ΔT) by adding thedetection value Td of the temperature sensor (46) to a temperatureincrease ΔT from an installation part of the temperature sensor (46) toeach electrical connection part of the power element(s) (37) (step S37).Note that the temperature increase AT may be a value measured by a testin advance or may be a value estimated based on thermal resistance and athermal flow rate. Then, the dew condensation determinator (54) refersto a detection value (outdoor air temperature) Ta of an outdoor airtemperature sensor (41) (step S38).

Subsequently, the dew condensation determinator (54) determines whetheror not a dew condensation state in which the dew condensation is highlylikely to occur in the cooler (16) is established (step S39). Note that,when the temperature (Td+ΔT) is lower than the outdoor air temperatureTa, the dew condensation determinator (54) determines that the dewcondensation state is established.

When the dew condensation determinator (54) determines that the dewcondensation state is established, a forcible opening degree reducer(55) forcibly reduces the degree of opening of a first throttle valve(18) by a predetermined value on behalf of a first opening degreeadjuster (52) (step S40).

When the degree of opening of the first throttle valve (18) is forciblyreduced, the amount of refrigerant flowing into a branch circuit (10B)is reduced, and therefore the amount of heat absorbed by refrigerant inthe cooler (16) (the amount of heat dissipated from a power module (61))is reduced. Thus, the dew condensation in the power module (61) andsurrounding components (16, 71) thereof is reduced, and the dewcondensation state in the cooler (16) is cleared.

After the degree of opening of the first throttle valve (18) is forciblyreduced by the forcible opening degree reducer (55) as described above,the process returns to step S36, and the operation control device (50)repeats the same process. As a result, while the dew condensationdeterminator (54) determines that the dew condensation state isestablished, the degree of opening of the first throttle valve (18) isreduced by the forcible opening degree reducer (55) every time the dewcondensation reduction operation control is performed. When the dewcondensation determinator (54) no longer determines that the dewcondensation state is established, the operation control device (50)resumes a normal operation control, and adjusts the degree of opening ofthe first throttle valve (18) such that the evaporation temperature ofrefrigerant in the cooler (16) reaches a target temperature.

Advantages of Fourth Embodiment

According to the fourth embodiment, since the temperature sensor (46)and the outdoor air temperature sensor (41) are used, it can be easilydetected with high accuracy that the dew condensation is highly likelyto occur in the power element(s) (37) or the surrounding components (16,71) thereof. In addition, when the possibility of the occurrence of thedew condensation is increased, the degree of opening of the firstthrottle valve (18) is reduced, thereby reducing a decrease intemperature of the cooler (16). Thus, the occurrence of the dewcondensation can be prevented.

Even under the temperature environment under which the dew condensationoccurs around the cooler (16) during the operation of the refrigerationapparatus (1), the electrical connection part of the power element(s)(37) where a short circuit may occur due to adherence of dewcondensation water may not actually be, because of heat generation ofthe power element(s) (37), under the temperature environment under whichthe dew condensation occurs. In the fourth embodiment, when theestimated temperature of the electrical connection part of the powerelement(s) (37) where the short circuit may occur due to the adherenceof dew condensation water is lower than an air temperature, the degreeof opening of the first throttle valve (18) is forcibly reduced by theforcible opening degree reducer (55), thereby preventing the occurrenceof the dew condensation. The temperature of refrigerant in the cooler(16) can be reduced to the lowest possible temperature at which the dewcondensation does not occur in the electrical part of the powerelement(s) (37). Thus, breakdown of the power element(s) (37) can beprevented, and performance of the cooler (16) can be improved.

Note that the temperature sensor (46) may be attached to the powerelement(s) (37) (in the present embodiment, the power module (61)) orthe surrounding components (e.g., the substrate (71)) thereof.

In the fourth embodiment, the outdoor air temperature sensor (41) isused as the air temperature sensor of the present invention. However,the air temperature sensor of the present invention may be any sensorsother than the outdoor air temperature sensor (41) as long as thetemperature of air around a power supply device (30) is detectable, andmay be a sensor configured to detect the temperature of air around thepower supply device (30) in a heat-source-side unit (1A).

Fifth Embodiment of the Invention

As illustrated in FIG. 9, in a refrigeration apparatus (1) of a fifthembodiment, a humidity sensor (47) is provided near power element(s)(37) instead of providing the dew condensation sensor (45) of the firstembodiment, and is used as a detector configured to detect a physicalamount based on which it is determined whether or not a dew condensationstate is established.

The humidity sensor (47) is connected to an operation control device(50), and transmits a detection signal to the operation control device(50). When a detection value of the humidity sensor (47) is higher thana predetermined upper limit, a dew condensation determinator (54) of theoperation control device (50) determines that the dew condensation statein which dew condensation occurs in the power element(s) (37) andsurrounding components (16, 71) thereof is established. Since otherconfigurations of the present embodiment are similar to those of thefirst embodiment, the description thereof will not be repeated.

A refrigeration cycle, cooling of the power element(s), and a normaloperation control by the operation control device (50) are similar tothose of the first embodiment. A dew condensation reduction operationcontrol by the operation control device (50) will be described below.

As illustrated in FIG. 10, the dew condensation determinator (54) firstrefers to a detection value Hp of the humidity sensor (47) (step S41).

Next, the dew condensation determinator (54) determines whether or notthe dew condensation state in which the dew condensation is highlylikely to occur in the power element(s) (37) or the surroundingcomponents (16, 71) thereof is established (step S42). Note that, whenthe detection value Hp of the humidity sensor (47) is higher than apredetermined upper limit Hm, the dew condensation determinator (54)determines that the dew condensation state is established.

Then, when the dew condensation determinator (54) determines at step S42that the dew condensation state is established, a forcible openingdegree reducer (55) forcibly reduces the degree of opening of a firstthrottle valve (18) by a predetermined value on behalf of a firstopening degree adjuster (52) (step S43).

When the degree of opening of the first throttle valve (18) is forciblyreduced, the amount of refrigerant flowing into a branch circuit (10B)is reduced, and therefore the amount of heat absorbed by refrigerant ina cooler (16) (the amount of heat dissipated from a power module (61))is reduced. Thus, the dew condensation in the power module (61) and thesurrounding components (16, 71) thereof is reduced, and the dewcondensation state in the cooler (16) is cleared.

After the degree of opening of the first throttle valve (18) is forciblyreduced by the forcible opening degree reducer (55) as described above,the process returns to step S41, and the operation control device (50)repeats the same process. As a result, while the dew condensationdeterminator (54) determines that the dew condensation state isestablished, the degree of opening of the first throttle valve (18) isreduced by the forcible opening degree reducer (55) every time the dewcondensation reduction operation control is performed. When the dewcondensation determinator (54) no longer determines that the dewcondensation state is established, the operation control device (50)resumes the normal operation control, and adjusts the degree of openingof the first throttle valve (18) such that the evaporation temperatureof refrigerant in the cooler (16) reaches a target temperature.

Advantages of Fifth Embodiment

In the fifth embodiment, since the humidity sensor (47) is used, it canbe easily detected with high accuracy that the dew condensation ishighly likely to occur in the power element(s) (37) or the surroundingcomponents (16, 71) thereof. In addition, when the possibility of theoccurrence of the dew condensation is increased, the degree of openingof the first throttle valve (18) is forcibly reduced, thereby reducing adecrease in temperature of the cooler (16). Thus, the occurrence of thedew condensation can be prevented.

Sixth Embodiment of the Invention

As illustrated in FIG. 11, a refrigeration apparatus (1) of a sixthembodiment is configured by adding a humidity sensor (48) configured todetect the humidity of air around a power supply device (30) to therefrigeration apparatus (1) of the second embodiment. In therefrigeration apparatus (1) of the sixth embodiment, the humidity sensor(48), an outdoor air temperature sensor (41), and a temperature sensor(46) are used as detectors each configured to detect a physical amountbased on which it is determined whether or not a dew condensation stateis established.

The humidity sensor (48) is configured to detect the humidity of outdoorair before the outdoor air reaches a cooler (16), and is providedupstream of the cooler (16) in an air flow. In addition, the humiditysensor (48) is connected to an operation control device (50), andtransmits a detection signal to the operation control device (50). Whena detection value of the temperature sensor (46) is lower than adew-point temperature calculated based on a detection value of thehumidity sensor (48) and a detection value of the outdoor airtemperature sensor (41), a dew condensation determinator (54) of theoperation control device (50) determines that the dew condensation statein which dew condensation is highly likely to occur in power element(s)(37) and surrounding components (16, 71) thereof is established. Sinceother configurations of the present embodiment are similar to those ofthe second embodiment, the description thereof will not be repeated.

A refrigeration cycle, cooling of the power element(s), and a normaloperation control by the operation control device (50) are similar tothose of the first embodiment. A dew condensation reduction operationcontrol by the operation control device (50) will be described below.

As illustrated in FIG. 12, the dew condensation determinator (54) firstrefers to a detection value (outdoor air temperature) Ta of the outdoorair temperature sensor (41) and a detection value (outdoor air humidity)Ha of the humidity sensor (48) (step S44). Next, based on the detectionvalue Ta of the outdoor air temperature sensor (41) and the detectionvalue Ha of the humidity sensor (48), the dew condensation determinator(54) calculates a dew-point temperature Tw when an air temperature is Taand a relative humidity is Ha (step S45). Then, the dew condensationdeterminator (54) refers to a detection value (temperature Td of thecooler (16)) of the temperature sensor (46) (step S46).

Next, the dew condensation determinator (54) determines whether or notthe dew condensation state in which the dew condensation is highlylikely to occur in the cooler (16) is established (step S47). Note that,when the detection value Td of the temperature sensor (46) is lower thanthe dew-point temperature Tw, the dew condensation determinator (54)determines that the dew condensation state is established.

Then, when the dew condensation determinator (54) determines at step S47that the dew condensation state is established, a forcible openingdegree reducer (55) forcibly reduces the degree of opening of a firstthrottle valve (18) by a predetermined value on behalf of a firstopening degree adjuster (52) (step S48).

When the degree of opening of the first throttle valve (18) is forciblyreduced, the amount of refrigerant flowing into a branch circuit (10B)is reduced, and therefore the amount of heat absorbed by refrigerant inthe cooler (16) (the amount of heat dissipated from a power module (61))is reduced. Thus, the dew condensation in the power module (61) and thesurrounding components (16, 71) thereof is reduced, and the dewcondensation state in the cooler (16) is cleared.

After the degree of opening of the first throttle valve (18) is forciblyreduced by the forcible opening degree reducer (55) as described above,the process returns to step S44, and the operation control device (50)repeats the same process. As a result, while the dew condensationdeterminator (54) determines that the dew condensation state isestablished, the degree of opening of the first throttle valve (18) isreduced by the forcible opening degree reducer (55) every time the dewcondensation reduction operation control is performed. When the dewcondensation determinator (54) no longer determines that the dewcondensation state is established, the operation control device (50)resumes the normal operation control, and adjusts the degree of openingof the first throttle valve (18) such that the evaporation temperatureof refrigerant in the cooler (16) reaches a target temperature.

Advantages of Sixth Embodiment

In the sixth embodiment, the humidity sensor (48) configured to detectthe humidity of outdoor air before the outdoor air reaches the cooler(16), the outdoor air temperature sensor (41) similar to that of thesecond embodiment, and the temperature sensor (46) similar to that ofthe second embodiment are used as the detectors.

Based on the temperature and humidity of air (outdoor air) before theair is cooled by the cooler (16), the dew condensation determinator (54)calculates the dew-point temperature of the air, and determines, whenthe temperature around the power element(s) (37) is lower than thedew-point temperature, that the dew condensation state in which the dewcondensation is highly likely to occur in the power element(s) (37) isestablished.

Thus, according to the sixth embodiment, since the humidity sensor (48),the outdoor air temperature sensor (41), and the temperature sensor (46)are used, it can be easily detected with high accuracy that the dewcondensation is highly likely to occur in the power element(s) (37) orthe surrounding components (16, 71) thereof. In addition, since theamount of heat generation of the power element(s) (37) is increased whenthe possibility of the occurrence of the dew condensation is increased,the occurrence of the dew condensation can be prevented.

Under normal conditions, the cooler (16) configured to cool the powerelement(s) (37) has a temperature lower than that of the powerelement(s) (37) during the operation of the refrigeration apparatus (1).Since the temperature sensor (46) is attached to the cooler (16), thepossibility of the occurrence of the dew condensation can be detected ata relatively early stage. Thus, it can be further ensured that theoccurrence of the dew condensation in the power element(s) (37) and thesurrounding components (16, 71) thereof is prevented.

Note that the temperature sensor (46) may be attached to the powerelement(s) (37) (in the present embodiment, the power module (61)) orthe surrounding components (e.g., the substrate (71)) thereof.

In the sixth embodiment, the outdoor air temperature sensor (41) is usedas the air temperature sensor of the present invention. However, the airtemperature sensor of the present invention may be any sensors otherthan the outdoor air temperature sensor (41) as long as the temperatureof air around the power supply device (30) is detectable, and may be asensor configured to detect the temperature of air around the powersupply device (30) in a heat-source-side unit (1A).

Seventh Embodiment of the Invention

As illustrated in FIG. 13, a refrigeration apparatus (1) of a seventhembodiment is configured by changing the configuration of the operationcontrol device (50) of the first embodiment.

Specifically, in the seventh embodiment, an operation control device(50) includes a normal operator (51) and a dew condensation determinator(54) which are similar to those of the first embodiment. In addition,the operation control device (50) further includes a heat generationamount increaser (56) and a heat generation amount resetter (57),instead of including the forcible opening degree reducer (55) of thefirst embodiment.

When the dew condensation determinator (54) determines that a dewcondensation state is established, the heat generation amount increaser(56) increases the amount of heat generation of power element(s) (37).Note that, in the present embodiment, the heat generation amountincreaser (56) increases a current value of a compressor (11), therebyincreasing the amount of heat generation of the power element(s) (37) ina drive circuit (31) for the compressor (11).

When the dew condensation determinator (54) determines that the dewcondensation state is not established, the heat generation amountresetter (57) resets the amount of heat generation of the powerelement(s) (37) of the power module (61) increased by the heatgeneration amount increaser (56) to a normal state before the increasein heat generation amount. That is, the heat generation amount resetter(57) resets a current value of a motor (11 a) of the compressor (11) toa normal state before the increase in current value, thereby resettingthe amount of heat generation of the power element(s) (37) in the drivecircuit (31) for the compressor (11) to the normal state.

The heat generation amount increaser (56) serves as a temperatureincreaser (91) of the present invention configured to increase thetemperature of the power element(s) (37). On the other hand, the heatgeneration amount resetter (57) serves as a temperature resetter (92)configured to reset the temperature of the power element(s) (37)increased by the temperature increaser (91) to a normal state.

A refrigeration cycle, cooling of the power element(s), and a normaloperation control by the operation control device (50) are similar tothose of the first embodiment. A dew condensation reduction operationcontrol by the operation control device (50) will be described below.

As illustrated in FIG. 14, the dew condensation determinator (54) firstrefers to a dew condensation signal from a dew condensation sensor (45)(step S51), and then determines whether or not the dew condensationstate in which dew condensation occurs in a cooler (16) is established(step S52). Then, when the dew condensation determinator (54) determinesthat the dew condensation state is established, the heat generationamount increaser (56) increases the amount of heat generation of thepower element(s) (37) (step S53).

Note that, in the present embodiment, the heat generation amountincreaser (56) increases the current value of the compressor (11),thereby increasing the amount of heat generation of the power element(s)(37) in the drive circuit (31) for the compressor (11).

Of various power elements (37), only the amount of heat generation ofthe power element(s) (37) in the drive circuit (31) for the compressor(11) is increased in the foregoing state. However, the various powerelements (37) together form the single power module (61). Thus, theamount of heat generation of the power element(s) (37) controlling thecompressor (11) is increased, resulting in an increase in temperature ofthe entirety of the power module (61). Consequently, the dewcondensation in the power module (61) and surrounding components (16,71) thereof is reduced, and the dew condensation state in the cooler(16) is cleared.

After the amount of heat generation of the power element(s) (37) in thedrive circuit (31) for the compressor (11) is increased as describedabove, the dew condensation determinator (54) refers to a dewcondensation signal from the dew condensation sensor (45) (step S54),and determines whether or not the dew condensation state in the cooler(16) is cleared (step S55). Then, when the dew condensation determinator(54) determines that the dew condensation state is not cleared, theprocess returns to step S54 with the amount of heat generation of thepower element(s) (37) being increased, and the dew condensationdeterminator (54) refers to a dew condensation signal of the dewcondensation sensor (45) again.

On the other hand, when the dew condensation determinator (54)determines at step S55 that the dew condensation state is cleared, theheat generation amount resetter (57) resets the amount of heatgeneration of the power element(s) (37) in the drive circuit (31) forthe compressor (11) to the normal state before the increase in heatgeneration amount (step S56). Then, the process returns to step S51, andthe foregoing flow is repeated.

Advantages of Seventh Embodiment

As described above, according to the seventh embodiment, when the dewcondensation determinator (54) determines that the dew condensationstate in which the dew condensation occurs in the cooler (16) isestablished, the amount of heat generation of the power element(s) (37)is increased by the heat generation amount increaser (56), therebyincreasing the temperature of the power element(s) (37) and thesurrounding components (16, 71) thereof. As a result, the occurrence ofthe dew condensation in the power element(s) (37) and the surroundingcomponents (16, 71) thereof can be reduced, and corrosion of, e.g.,metal components arranged near the power element(s) (37) and thesurrounding components (16, 71) thereof and degradation of insulatingperformance of the power element(s) (37) can be prevented.

According to the seventh embodiment, the amount of heat generation ofthe power element(s) (37) is increased not when it is assumed that thedew condensation state is established, but when it is determined byusing the dew condensation sensor (45) that the dew condensation statein which the dew condensation actually occurs in the cooler (16) isestablished. Thus, when the dew condensation does not actually occur,the amount of heat generation of the power element(s) (37) is notuselessly increased. Consequently, a loss caused due to the increase inamount of heat generation of the power element(s) (37) can be reduced.

According to the seventh embodiment, since the dew condensation sensor(45) is used, the occurrence of the dew condensation can be easilydetected with high accuracy.

Under normal conditions, the cooler (16) configured to cool the powerelement(s) (37) has a temperature lower than that of the powerelement(s) (37) during the operation of the refrigeration apparatus (1).Thus, it is likely that the dew condensation occurs in the cooler (16)before the dew condensation occurs in the power element(s) (37).

In the seventh embodiment, since the dew condensation sensor (45) isattached to the cooler (16), the occurrence of the dew condensation canbe detected at a relatively early stage. Thus, e.g., when the dewcondensation occurs in the cooler (16) and does not occur in the powerelement(s) (37), the amount of heat generation of the power element(s)(37) can be increased. This prevents the occurrence of the dewcondensation in the power element(s) (37).

Note that the dew condensation sensor (45) may be attached to the powerelement(s) (37) (in the present embodiment, the power module (61)) orthe surrounding components (e.g., the substrate (71)) thereof.

According to the seventh embodiment, the dew condensation sensor (45)can detect with high accuracy that the dew condensation state iscleared. As soon as the dew condensation state is cleared, the amount ofheat generation of the power element(s) (37) can be, by the heatgeneration amount resetter (57), reset to the normal state before theincrease in heat generation amount. Thus, a heat loss caused due to theincrease in amount of heat generation of the power element(s) (37) canbe suppressed to the minimum.

According to the seventh embodiment, the current value of the compressor(11) is increased, and therefore the amount of heat generation of thepower element(s) (37) provided for the compressor (11) is increased. Insuch a manner, the temperature of the entirety of the power module (61)formed by the various power element(s) (37) can be increased.Consequently, the temperature of the power element(s) (37) can be easilyincreased, e.g., without using a heating unit such as a heater. As aresult, the occurrence of the dew condensation in the power element(s)(37) and the surrounding components (16, 71) thereof can be easilyreduced.

Eighth Embodiment of the Invention

In a refrigeration apparatus (1) of an eighth embodiment, a temperaturesensor (46) similar to that of the second embodiment is provided insteadof providing the dew condensation sensor (45) of the seventh embodiment(see FIG. 5). As in the second embodiment, an outdoor air temperaturesensor (41) is used as the air temperature sensor of the presentinvention configured to detect the temperature of air around a powersupply device (30). In addition, in the refrigeration apparatus (1) ofthe eighth embodiment, the temperature sensor (46) and the outdoor airtemperature sensor (41) are used as detectors each configured to detecta physical amount based on which it is determined whether or not a dewcondensation state is established.

As in the second embodiment, when a detection value of the temperaturesensor (46) is lower than a detection value of the outdoor airtemperature sensor (41), a dew condensation determinator (54) of anoperation control device (50) determines that the dew condensation statein which dew condensation occurs in power element(s) (37) andsurrounding components (16, 71) thereof is established. Since otherconfigurations of the present embodiment are similar to those of theseventh embodiment, the description thereof will not be repeated.

A refrigeration cycle, cooling of the power element(s), and a normaloperation control by the operation control device (50) are similar tothose of the seventh embodiment. A dew condensation reduction operationcontrol by the operation control device (50) will be described below.

As illustrated in FIG. 15, the dew condensation determinator (54) firstrefers to a detection value (outdoor air temperature) Ta of the outdoorair temperature sensor (41) (step S61), and then refers to a detectionvalue (temperature of a cooler (16)) Td of the temperature sensor (46)(step S62).

Next, the dew condensation determinator (54) determines whether or notthe dew condensation state in which the dew condensation is highlylikely to occur in the cooler (16) is established (step S63). Note that,when the detection value Td of the temperature sensor (46) is lower thanthe detection value Ta of the outdoor air temperature sensor (41), thedew condensation determinator (54) determines that the dew condensationstate is established.

Then, when the dew condensation determinator (54) determines at step S63that the dew condensation state is established, a heat generation amountincreaser (56) increases the amount of heat generation of the powerelement(s) (37) (step S64).

After the heat generation amount increaser (56) increases the amount ofheat generation of the power element(s) (37), the dew condensationdeterminator (54) refers to the detection value Ta of the outdoor airtemperature sensor (41) (step S65), and then refers to the detectionvalue Td of the temperature sensor (46) (step S66).

Next, the dew condensation determinator (54) determines whether or notthe dew condensation state is cleared (step S67). Note that, when thedetection value Td of the temperature sensor (46) reaches a value equalto or greater than the detection value Ta of the outdoor air temperaturesensor (41), the dew condensation determinator (54) determines that thedew condensation state is cleared.

When the dew condensation determinator (54) determines at step S67 thatthe dew condensation state is not cleared, the process returns to stepS65 with the amount of heat generation of the power element(s) (37)being increased, and the dew condensation determinator (54) refers to adetection value Ta of the outdoor air temperature sensor (41) and thedetection value Td of the temperature sensor (46) again.

On the other hand, when the dew condensation determinator (54)determines at step S67 that the dew condensation state is cleared, theheat generation amount resetter (57) resets the amount of heatgeneration of the power element(s) (37) to a normal state before theincrease in heat generation amount (step S68). Then, the process returnsto step S61, and the foregoing flow is repeated.

Advantages of Eighth Embodiment

According to the eighth embodiment, since the temperature sensor (46)and the outdoor air temperature sensor (41) are used as in the secondembodiment, it can be easily detected with high accuracy that the dewcondensation is highly likely to occur in the power element(s) (37) orthe surrounding components (16, 71) thereof. In addition, when thepossibility of the occurrence of the dew condensation is increased, theamount of heat generation of the power element(s) (37) is increased.Thus, the occurrence of the dew condensation can be prevented.

Ninth Embodiment of the Invention

A refrigeration apparatus (1) of a ninth embodiment is configuredsimilar to that of the eighth embodiment, except that a method fordetermining occurrence of dew condensation by a dew condensationdeterminator (54) of an operation control device (50) is different. Notethat the method for determining the occurrence of the dew condensationis similar to that of the third embodiment. A dew condensation reductionoperation control by the operation control device (50) which isdifferent from that of the eighth embodiment will be described below.

As illustrated in FIG. 16, the dew condensation determinator (54) firstrefers to a detection value (outdoor air temperature) Ta of an outdoorair temperature sensor (41) (step S71). Next, based on the detectionvalue Ta of the outdoor air temperature sensor (41), the dewcondensation determinator (54) calculates a dew-point temperature Twwhen an air temperature is Ta and a relative humidity is H1 (step S72).Then, the dew condensation determinator (54) refers to a detection value(temperature Td of a cooler (16)) of a temperature sensor (46) (stepS73).

Subsequently, the dew condensation determinator (54) determines whetheror not a dew condensation state in which the dew condensation is highlylikely to occur in the cooler (16) is established (step S74). Note that,when the detection value Td of the temperature sensor (46) is lower thanthe dew-point temperature Tw, the dew condensation determinator (54)determines that the dew condensation state is established.

When the dew condensation determinator (54) determines that the dewcondensation state is established, a heat generation amount increaser(56) increases the amount of heat generation of the power element(s)(37) (step S75).

After the heat generation amount increaser (56) increases the amount ofheat generation of the power element(s) (37), the dew condensationdeterminator (54) refers to the detection value Ta of the outdoor airtemperature sensor (41) (step S76). Next, the dew condensationdeterminator (54) calculates the dew-point temperature Tw when the airtemperature is Ta and the relative humidity is H1 (step S77). Then, thedew condensation determinator (54) refers to the detection value Td ofthe temperature sensor (46) (step S78).

Subsequently, the dew condensation determinator (54) determines whetheror not the dew condensation state is cleared (step S79). Note that, whenthe detection value Td of the temperature sensor (46) reaches a valueequal to or higher than the calculated dew-point temperature Tw, the dewcondensation determinator (54) determines that the dew condensationstate is cleared.

When the dew condensation determinator (54) determines at step S79 thatthe dew condensation state is not cleared, the process returns to stepS76 with the amount of heat generation of the power element(s) (37)being increased. Then, the dew condensation determinator (54) calculatesthe dew-point temperature Tw based on the detection value Ta of theoutdoor air temperature sensor (41) and the relative humidity H1 again,and refers to the detection value Td of the temperature sensor (46).

On the other hand, when the dew condensation determinator (54)determines at step S79 that the dew condensation state is cleared, theheat generation amount resetter (57) resets the amount of heatgeneration of the power element(s) (37) to a normal state before theincrease in heat generation amount (step S80). Then, the process returnsto step S71, and the foregoing flow is repeated.

Advantages of Ninth Embodiment

According to the ninth embodiment, since the temperature sensor (46) andthe outdoor air temperature sensor (41) are used as in the thirdembodiment, it can be easily detected with high accuracy that the dewcondensation is highly likely to occur in the power element(s) (37) orsurrounding components (16, 71) thereof. In addition, when thepossibility of the occurrence of the dew condensation is increased, theamount of heat generation of the power element(s) (37) is increased.Thus, the occurrence of the dew condensation can be prevented.

Tenth Embodiment of the Invention

A refrigeration apparatus (1) of a tenth embodiment is configuredsimilar to that of the eighth embodiment, except that a method fordetermining occurrence of dew condensation by a dew condensationdeterminator (54) of an operation control device (50) is different. Notethat the method for determining the occurrence of the dew condensationis similar to that of the fourth embodiment. A dew condensationreduction operation control by the operation control device (50) whichis different from that of the eighth embodiment will be described below.

As illustrated in FIG. 17, the dew condensation determinator (54) firstrefers to a detection value (temperature Td of a cooler (16)) of atemperature sensor (46) (step S91). Next, the dew condensationdeterminator (54) calculates a temperature (Td+ΔT) by adding thedetection value Td of the temperature sensor (46) to a temperatureincrease ΔT from an installation part of the temperature sensor (46) toeach electrical connection part of power element(s) (37) (step S92).Note that the temperature increase ΔT may be a value measured by a testin advance or may be a value estimated based on thermal resistance and athermal flow rate. Then, the dew condensation determinator (54) refersto a detection value (outdoor air temperature) Ta of an outdoor airtemperature sensor (41) (step S93).

Subsequently, the dew condensation determinator (54) determines whetheror not a dew condensation state in which the dew condensation is highlylikely to occur in the cooler (16) is established (step S94). Note that,when the temperature (Td+ΔT) is lower than the outdoor air temperatureTa, the dew condensation determinator (54) determines that the dewcondensation state is established.

When the dew condensation determinator (54) determines that the dewcondensation state is established, a heat generation amount increaser(56) increases the amount of heat generation of the power element(s)(37) (step S95).

After the heat generation amount increaser (56) increases the amount ofheat generation of the power element(s) (37), the dew condensationdeterminator (54) refers to a detection value (temperature Td of thecooler (16)) of the temperature sensor (46) (step S96). Next, the dewcondensation determinator (54) calculates the temperature (Td+ΔT) byadding the detection value Td of the temperature sensor (46) to thetemperature increase ΔT from the installation part of the temperaturesensor (46) to the electrical connection part of the power element(s)(37) (step S97). Then, the dew condensation determinator (54) refers toa detection value (outdoor air temperature) Ta of the outdoor airtemperature sensor (41) (step S98).

Next, the dew condensation determinator (54) determines whether or notthe dew condensation state is cleared (step S99). Note that, when thetemperature (Td+ΔT) reaches a value equal to or greater than thedetection value Ta of the outdoor air temperature sensor (41), the dewcondensation determinator (54) determines that the dew condensationstate is cleared.

When the dew condensation determinator (54) determines at step S99 thatthe dew condensation state is not cleared, the process returns to stepS96 with the amount of heat generation of the power element(s) (37)being increased.

On the other hand, when the dew condensation determinator (54)determines at step S99 that the dew condensation state is cleared, aheat generation amount resetter (57) resets the amount of heatgeneration of the power element(s) (37) to a normal amount before theincrease in heat generation amount (step S100). Then, the processreturns to step S91, and the foregoing flow is repeated.

Advantages of Tenth Embodiment

According to the tenth embodiment, since the temperature sensor (46) andthe outdoor air temperature sensor (41) are used as in the fourthembodiment, it can be easily detected with high accuracy that the dewcondensation is highly likely to occur in the power element(s) (37) orsurrounding components (16, 71) thereof. In addition, when thepossibility of the occurrence of the dew condensation is increased, theamount of heat generation of the power element(s) (37) is increased.Thus, the occurrence of the dew condensation can be prevented.

Even under the temperature environment under which the dew condensationoccurs around the cooler (16) during the operation of the refrigerationapparatus (1), the electrical connection part of the power element(s)(37) where a short circuit may occur due to adherence of dewcondensation water may not actually be, because of heat generation ofthe power element(s) (37), under the temperature environment under whichthe dew condensation occurs. In the tenth embodiment, when the estimatedtemperature of the electrical connection part of the power element(s)(37) where the short circuit may occur due to the adherence of dewcondensation water is lower than an air temperature, the temperature ofthe power element(s) (37) is increased by the temperature increaser(91). Thus, when the dew condensation may not actually occur in theelectrical connection part of the power element(s) (37) where the shortcircuit may occur due to the adherence of dew condensation water, thetemperature of the power element(s) (37) is not uselessly increased bythe temperature increaser (91). Consequently, breakdown of the powerelement(s) (37) can be prevented without uselessly increasing the amountof heat generation of the power element(s) (37).

Eleventh Embodiment of the Invention

In a refrigeration apparatus (1) of an eleventh embodiment, a humiditysensor (47) similar to that of the fifth embodiment is provided nearpower element(s) (37) instead of providing the dew condensation sensor(45) of the seventh embodiment (see FIG. 9), and is used as a detectorconfigured to detect a physical amount based on which it is determinedwhether or not a dew condensation state is established.

As in the fifth embodiment, a dew condensation determinator (54) of anoperation control device (50) is configured to determine, when adetection value of the humidity sensor (47) is higher than apredetermined upper limit, that the dew condensation state in which dewcondensation occurs in the power element(s) (37) and surroundingcomponents (16, 71) thereof is established. Since other configurationsof the present embodiment are similar to those of the seventhembodiment, the description thereof will not be repeated.

A refrigeration cycle, cooling of the power element(s), and a normaloperation control by the operation control device (50) are similar tothose of the seventh embodiment. A dew condensation reduction operationcontrol by the operation control device (50) will be described below.

As illustrated in FIG. 18, the dew condensation determinator (54) firstrefers to a detection value Hp of the humidity sensor (47) (step S81).

Next, the dew condensation determinator (54) determines whether or notthe dew condensation state in which the dew condensation is highlylikely to occur in the power element(s) (37) or the surroundingcomponents (16, 71) thereof is established (step S82). Note that, whenthe detection value Hp of the humidity sensor (47) is higher than apredetermined upper limit Elm, the dew condensation determinator (54)determines that the dew condensation state is established.

Then, when the dew condensation determinator (54) determines at step S82that the dew condensation state is established, a heat generation amountincreaser (56) increases the amount of heat generation of the powerelement(s) (37) (step S83).

After the heat generation amount increaser (56) increases the amount ofheat generation of the power element(s) (37), the dew condensationdeterminator (54) refers to the detection value Hp of the humiditysensor (47) (step S84), and then determines whether or not the dewcondensation state is cleared (step S85). Note that, when the detectionvalue Hp of the humidity sensor (47) reaches a value equal to or lessthan the predetermined upper limit Hm, the dew condensation determinator(54) determines that the dew condensation state is cleared.

When the dew condensation determinator (54) determines at step S85 thatthe dew condensation state is not cleared, the process returns to stepS84 with the amount of heat generation of the power element(s) (37)being increased, and the dew condensation determinator (54) refers to adetection value of the humidity sensor (47) again.

On the other hand, when the dew condensation determinator (54)determines at step S85 that the dew condensation state is cleared, aheat generation amount resetter (57) resets the amount of heatgeneration of the power element(s) (37) to a normal state before theincrease in heat generation amount (step S86). Then, the process returnsto step S81, and the foregoing flow is repeated.

Advantages of Eleventh Embodiment

According to the eleventh embodiment, since the humidity sensor (47) isused, it can be easily detected with high accuracy that the dewcondensation is highly likely to occur in the power element(s) (37) orthe surrounding components (16, 71) thereof. In addition, when thepossibility of the occurrence of the dew condensation is increased, theamount of heat generation of the power element(s) (37) is increased.Thus, the occurrence of the dew condensation can be prevented.

Twelfth Embodiment of the Invention

A refrigeration apparatus (1) of a twelfth embodiment is configured byadding a humidity sensor (48) similar to that of the sixth embodiment tothe refrigeration apparatus (1) of the eighth embodiment (see FIG. 11).The humidity sensor (48), an outdoor air temperature sensor (41), and atemperature sensor (46) are used as detectors each configured to detecta physical amount based on which it is determined whether or not a dewcondensation state is established.

As in the sixth embodiment, a dew condensation determinator (54) of anoperation control device (50) is configured to determine, when adetection value of the temperature sensor (46) is lower than a dew-pointtemperature calculated based on a detection value of the humidity sensor(48) and a detection value of the outdoor air temperature sensor (41),that the dew condensation state in which dew condensation is highlylikely to occur in power element(s) (37) and surrounding components (16,71) thereof is established. Since other configurations of the presentembodiment are similar to those of the eighth embodiment, thedescription thereof will not be repeated.

A refrigeration cycle, cooling of the power element(s), and a normaloperation control by the operation control device (50) are similar tothose of the eighth embodiment. A dew condensation reduction operationcontrol by the operation control device (50) will be described below.

As illustrated in FIG. 19, the dew condensation determinator (54) firstrefers to a detection value (outdoor air temperature) Ta of the outdoorair temperature sensor (41) and a detection value (outdoor air humidity)Ha of the humidity sensor (48) (step S101). Next, based on the detectionvalue Ta of the outdoor air temperature sensor (41) and the detectionvalue Ha of the humidity sensor (48), the dew condensation determinator(54) calculates a dew-point temperature Tw when an air temperature is Taand a relative humidity is Ha (step S102). Then, the dew condensationdeterminator (54) refers to a detection value (temperature Td of acooler (16)) of the temperature sensor (46) (step S103).

Next, the dew condensation determinator (54) determines whether or notthe dew condensation state in which the dew condensation is highlylikely to occur in the cooler (16) is established (step S104). Notethat, when the detection value Td of the temperature sensor (46) islower than the dew-point temperature Tw, the dew condensationdeterminator (54) determines that the dew condensation state isestablished.

After a heat generation amount increaser (56) increases the amount ofheat generation of the power element(s) (37), the dew condensationdeterminator (54) refers to a detection value (outdoor air temperature)Ta of the outdoor air temperature sensor (41) and the detection value(outdoor air humidity) Ha of the humidity sensor (48) (step S106). Next,based on the detection value Ta of the outdoor air temperature sensor(41) and the detection value Ha of the humidity sensor (48), the dewcondensation determinator (54) calculates the dew-point temperature Twwhen the air temperature is Ta and the relative humidity is Ha (stepS107). Then, the dew condensation determinator (54) refers to adetection value (temperature Td of the cooler (16)) of the temperaturesensor (46) (step S108).

Subsequently, the dew condensation determinator (54) determines whetheror not the dew condensation state is cleared (step S109). Note that,when the detection value Td of the temperature sensor (46) reaches avalue equal to or higher than the dew-point temperature Tw, the dewcondensation determinator (54) determines that the dew condensationstate is cleared.

When the dew condensation determinator (54) determines at step S109 thatthe dew condensation state is not cleared, the process returns to stepS106 with the amount of heat generation of the power element(s) (37)being increased.

On the other hand, when the dew condensation determinator (54)determines at step S109 that the dew condensation state is cleared, aheat generation amount resetter (57) resets the amount of heatgeneration of the power element(s) (37) to a normal state before theincrease in heat generation amount (step S110). Then, the processreturns to step S101, and the foregoing flow is repeated.

Advantages of Twelfth Embodiment

In the twelfth embodiment, the humidity sensor (48) configured to detectthe humidity of outdoor air before the outdoor air reaches the cooler(16), the outdoor air temperature sensor (41) similar to that of theeighth embodiment, and the temperature sensor (46) similar to that ofthe eighth embodiment are used as the detectors.

Based on the temperature and humidity of air (outdoor air) before theair is cooled by the cooler (16), the dew condensation determinator (54)calculates the dew-point temperature of the air. When the temperaturearound the power element(s) (37) is lower than the dew-pointtemperature, the dew condensation determinator (54) determines that thedew condensation state in which the dew condensation is highly likely tooccur in the power element(s) (37) is established.

Thus, according to the twelfth embodiment, since the humidity sensor(48), the outdoor air temperature sensor (41), and the temperaturesensor (46) are used, it can be easily detected with high accuracy thatthe dew condensation is highly likely to occur in the power element(s)(37) or the surrounding components (16, 71) thereof. In addition, whenthe possibility of the occurrence of the dew condensation is increased,the amount of heat generation of the power element(s) (37) is increased.Thus, the occurrence of the dew condensation can be prevented.

Thirteenth Embodiment of the Invention

In the seventh to twelfth embodiments, the heat generation amountincreaser (56) increases the current value of the compressor (11),thereby increasing the amount of heat generation of the power element(s)(37). In a thirteenth embodiment, a heat generation amount increaser(56) is configured to increase the switching frequency of a switchingelement(s) serving as a power element(s) (37) to increase the amount ofheat generation of the power element(s) (37).

Specifically, in a control device (60), the frequency (carrierfrequency) of a modulation signal to be used when a control signal froman operation control device (50) is converted into a drive signal isincreased. Thus, the frequency of the drive signal to be input from thecontrol device (60) to a base circuit of the switching element(s) of adrive circuit (31) is increased, thereby increasing the switchingfrequency of the switching element(s). That is, the state illustrated inFIG. 20( a) transitions to the state illustrated in FIG. 20( b). As aresult, since a heat loss due to switching is increased by an increasein switching frequency, the amount of heat generation of the powerelement(s) (37) is increased.

In the foregoing configuration, the amount of heat generation of thepower element(s) (37) can be easily increased without using a heatingunit such as a heater, and therefore occurrence of dew condensation inthe power element(s) (37) or surrounding components (16, 71) thereof canbe reduced.

Fourteenth Embodiment of the Invention

In the seventh to twelfth embodiments, the heat generation amountincreaser (56) increases the current value of the compressor (11),thereby increasing the amount of heat generation of the power element(s)(37). In a fourteenth embodiment, a heat generation amount increaser(56) is configured to increase a switching loss of a switchingelement(s) serving as a power element(s) (37) to increase the amount ofheat generation of the power element(s) (37).

Specifically, e.g., a time after an increase in resistance of a basecircuit until base voltage builds up (a turn-on time required until thebase circuit increases current to the maximum value and a turn-off timerequired until the base circuit cuts off current) is extended, andtherefore the switching loss is increased.

More specifically, e.g., a base circuit (70) illustrated in FIG. 21( a)is connected to the switching element. Switches A and B are closed in anormal operation, whereas the switch B is opened in a dew condensationreduction operation. As a result, as illustrated in FIG. 21( b), thetime required until the base voltage of the switching element is builtup is longer than that in the normal operation (changed from the stateindicated by a dashed line to the state indicated by a solid line inFIG. 21( b)), resulting in an increase in time for which the switchingloss is large. Thus, the loss per switching is increased, therebyincreasing the amount of heat generation of the power element(s) (37).

Alternatively, e.g., a time after an increase in capacity of a capacitorof the base circuit until the base voltage is built up (a turn-on timerequired until the base circuit increases current to the maximum valueand a turn-off time required until the base circuit cuts off current)may be extended, and therefore the switching loss may be increased.

Specifically, e.g., a base circuit (80) illustrated in FIG. 21( c) isconnected to the switching element. In the normal operation, only aswitch A is closed, and a switch B is opened. In the dew condensationreduction operation, the switch B is closed. As a result, as in the casewhere the resistance of the base circuit is increased, the time untilthe base voltage of the switching element is built up is longer thanthat in the normal operation (changed from the state indicated by thedashed line to the state indicated by the solid line in FIG. 21( b)),resulting in an increase in time for which the switching loss is large.Thus, the loss per switching is increased, thereby increasing the amountof heat generation of the power element(s) (37).

In the foregoing configuration, the amount of heat generation of thepower element(s) (37) can be easily increased without using a heatingunit such as a heater, and therefore occurrence of dew condensation inthe power element(s) (37) or surrounding components (16, 71) thereof canbe reduced.

The base circuit (70) illustrated in FIG. 21( a) has been set forth asan example of a circuit, the resistance of which is variable. The basecircuit (80) illustrated in FIG. 21( c) has been set forth as an exampleof a circuit, the capacity of the capacitor of which is variable. Thebase circuit (70, 80) is not limited to the foregoing examples.

Fifteenth Embodiment of the Invention

In the seventh to twelfth embodiments, the heat generation amountincreaser (56) increases the current value of the compressor (11),thereby increasing the amount of heat generation of the power element(s)(37). In a fifteenth embodiment, a heat generation amount increaser (56)is configured to increase a conduction loss of a power element(s) (37)to increase the amount of heat generation of the power element(s) (37).

Any methods may be employed to increase the conduction loss of the powerelement(s) (37). As a first example, the conduction loss of the powerelement(s) (37) may be increased by shifting the phase of currentflowing into each of drivers of a drive circuit (31) in a dewcondensation reduction operation. Specifically, as illustrated in FIG.22, in a normal operation, a refrigeration apparatus (1) is operatedusing a phase P1 that the conduction loss of the power element(s) (37)is the minimum. On the other hand, in the dew condensation reductionoperation, the refrigeration apparatus (1) is operated using a phase P2that the conduction loss of the power element(s) (37) is larger. Theshift from the phase P1 to the phase P2 as described above increasescollector current of the power element(s) (37), resulting in an increasein conduction loss of the power element(s) (37).

As a second example of increasing the conduction loss of the powerelement(s) (37), emitter-collector voltage of the power element(s) (37)of the drive circuit (31) may fluctuate in the dew condensationreduction operation. Specifically, as illustrated in FIG. 23, in thenormal operation, the emitter-collector voltage is maintained constant(see a dashed line in FIG. 23). On the other hand, the emitter-collectorvoltage fluctuates in the dew condensation reduction operation (see asolid line in FIG. 23). The fluctuation of the emitter-collector voltageincreases an effective value of the collector current, resulting in anincrease in conduction loss of the power element(s) (37).

For example, the following method for fluctuating the emitter-collectorvoltage may be employed. As illustrated in FIG. 24, a switch C isprovided in a capacitor circuit (33) of the drive circuit (31). In thenormal operation, the switch C is closed, and the emitter-collectorvoltage is smoothed by a capacitor (36). On the other hand, in the dewcondensation reduction operation, the switch C is opened to fluctuatethe emitter-collector voltage.

As a third example of increasing the conduction loss of the powerelement(s) (37), e.g., base voltage of the power element(s) (37) may belowered in the dew condensation reduction operation. The lowering of thebase voltage of the power element(s) (37) increases on-resistance(emitter-collector resistance in a conduction state) of the powerelement(s) (37), resulting in an increase in conduction loss of thepower element(s) (37).

The heat generation amount increaser (56) can increase the conductionloss of the power element(s) (37) by the foregoing methods to increasethe amount of heat generation of the power element(s) (37). Thus, in theforegoing configuration, the amount of heat generation of the powerelement(s) (37) can be easily increased without using a heating unitsuch as a heater, and therefore occurrence of dew condensation in thepower element(s) (37) or surrounding components (16, 71) thereof can bereduced.

Sixteenth Embodiment of the Invention

As illustrated in FIG. 25, a refrigeration apparatus (1) of a sixteenthembodiment is configured by changing the configuration of the operationcontrol device (50) of the refrigeration apparatus (1) of any one of theseventh to fifteenth embodiments.

Specifically, an operation control device (50) includes a forcible heatgeneration amount resetter (58) configured to, after a predeterminedtime has lapsed since the amount of heat generation of a powerelement(s) (37) was increased by a heat generation amount increaser(56), forcibly reset the amount of heat generation of the powerelement(s) (37) to a normal state before the increase in heat generationamount, in addition to a dew condensation determinator (54), the heatgeneration amount increaser (56), and a heat generation amount resetter(57).

The power element(s) (37) generates high-temperature heat, and tends tobe broken down when the temperature thereof is increased beyond a limittemperature. For such a reason, it is not preferable consideringprotection of the power element(s) (37) that the state in which theamount of heat generation of the power element(s) (37) is largecontinues for a long period of time. As in the eighth to twelfthembodiments, when dew condensation is highly likely to occur, it isdetermined that a dew condensation state is established, and then theamount of heat generation of the power element(s) (37) is increased. Insuch a case, although the dew condensation state is actually cleared,the dew condensation determinator (54) may determine that the dewcondensation state is established. Thus, there is a possibility that thestate in which the amount of heat generation of the power element(s)(37) is large continues uselessly.

In the sixteenth embodiment, a time sufficient for clearing the dewcondensation state is preset as the predetermined time. After thepredetermined time has lapsed since the amount of heat generation of thepower element(s) (37) was increased, the forcible heat generation amountresetter (58) forcibly resets the amount of heat generation of the powerelement(s) (37) to the normal state before the increase in heatgeneration amount. This prevents the breakdown of the power element(s)(37), and reduces a heat loss of the power element(s) (37).

In addition, e.g., a control by the heat generation amount increaser(56) is not allowed until a predetermined time has elapsed since theforcible heat generation amount resetter (58) forcibly resets the amountof heat generation of the power element(s) (37). In such a case, abalance between the reduction in dew condensation and the reduction inheat loss of the power element(s) (37) can be ensured.

Seventeenth Embodiment of the Invention

As illustrated in FIG. 26, a refrigeration apparatus (1) of aseventeenth embodiment is configured by changing the configuration ofthe temperature increaser (91) of the refrigeration apparatus (1) of theseventh embodiment.

Specifically, instead of the heat generation amount increaser (56) ofthe seventh embodiment, a temperature increaser (91) includes a heater(95) configured to heat a power element(s) (37), and a heater controller(96) configured to control ON/OFF of the heater (95). The heater (95) isprovided near the power element(s) (37), and the heater controller (96)is provided in an operation control device (50). Note that thetemperature resetter (92) also includes a heater (95) and a heatercontroller (96). Since other configurations of the present embodimentare similar to those of the seventh embodiment, the description thereofwill not be repeated.

An operation of the refrigeration apparatus (1) of the seventeenthembodiment is similar to that of the seventh embodiment, except that, ina dew condensation reduction operation control by the operation controldevice (50), the heater controller (96) performs an ON control of theheater (95) to increase the temperature of the power element(s) (37) atstep S53 and performs an OFF control of the heater (95) to reset thetemperature of the power element(s) (37) to a normal temperature beforethe increase in temperature of the power element(s) (37) at step S56.

As described above, since the heater (95) is used to increase thetemperature of the power element(s) (37), occurrence of dew condensationin the power element(s) (37) and surrounding components (16, 71) thereofmay be prevented.

In the refrigeration apparatus (1) of each of the eighth to twelfthembodiments, the configuration of the temperature increaser (91) may bechanged as in the foregoing.

Eighteenth Embodiment of the Invention

As illustrated in FIG. 27, a refrigeration apparatus (1) of aneighteenth embodiment is configured by changing part of a refrigerantcircuit (10) to which an outlet end of a branch circuit (10B) isconnected in each of the foregoing embodiments. Specifically, in theeighteenth embodiment, the outlet end of the branch circuit (10B) isconnected to a pipe on an inlet side of a compressor (11). Otherconfigurations of the present embodiment are similar to those of each ofthe foregoing embodiments. Note that, in FIG. 27, the refrigerationapparatus (1) configured by changing the configuration of the firstembodiment is illustrated as an example.

As described above, in the case where the outlet end of the branchcircuit (10B) is connected to the pipe on the inlet side of thecompressor (11), a first opening degree adjuster (52) adjusts, in thebranch circuit (10B), the degree of opening of a first throttle valve(18) such that the evaporation temperature of refrigerant in a cooler(16) reaches a target temperature. In addition, a second opening degreeadjuster (53) adjusts the degree of opening of a second throttle valve(17) such that the degree of superheating of refrigerant at an outlet ofthe cooler (16) reaches a target degree of superheating. Thus, thetemperature of refrigerant passing through the cooler (16) can be thetarget temperature, and moisturizing of refrigerant to be introducedinto the compressor (11) can be prevented.

In a dew condensation reduction operation control, when a dewcondensation determinator (54) determines that a dew condensation stateis established, occurrence of dew condensation in a power element(s)(37) and the cooler (16) can be reduced by forcibly reducing the degreeof opening of the first throttle valve (18) by a forcible opening degreereducer (55) on behalf of the first opening degree adjuster (52), or byincreasing the temperature of the power element(s) (37) by a temperatureincreaser (91).

Thus, advantages similar to those of each of the foregoing embodimentscan be realized in the eighteenth embodiment.

Nineteenth Embodiment of the Invention

As illustrated in FIG. 28, a refrigeration apparatus (1) of a nineteenthembodiment is configured such that, in each of the foregoingembodiments, a four-way valve (19) is provided in a refrigerant circuit(10) and refrigerant circulation in a main circuit (10A) is reversible.Note that, in FIG. 28, the refrigeration apparatus (1) configured bychanging the configuration of the first embodiment is illustrated as anexample.

Specifically, a gas pipe connected to an outlet side of a compressor(11) is connected to a first port (P1) of the four-way valve (19). A gaspipe connected to one end of a heat-source-side heat exchanger (12) isconnected to a second port (P2) of the four-way valve (19). A gas pipeconnected to an inlet side of the compressor (11) is connected to athird port (P3) of the four-way valve (19). A gas pipe connected to oneend of a utilization-side heat exchanger (14) is connected to a fourthport (P4) of the four-way valve (19).

Two inlet pipes (21, 22) are provided at an inlet end of a branchcircuit (10B). The two inlet pipes (21, 22) are connected to a liquidpipe connecting between the heat-source-side heat exchanger (12) and theutilization-side heat exchanger (14) so as to sandwich an expansionvalve (13). A check valve (23) configured to allow only a refrigerantflow from the main circuit (10A) to the inlet pipe (21) is provided inthe inlet pipe (21), and a check valve (24) configured to allow only arefrigerant flow from the main circuit (10A) to the inlet pipe (22) isprovided in the inlet pipe (22). Other configurations of the presentembodiment are similar to those of each of the foregoing embodiments.

According to the foregoing configuration, in the refrigeration apparatus(1) of the nineteenth embodiment, the refrigerant circulation in themain circuit (10A) is reversible, and, e.g., an air conditioningapparatus is switchable between an operation for cooling an inside of aroom and an operation for heating the inside of the room. Specifically,when the four-way valve (19) is switched to a first state (see a solidline in FIG. 28) in which the first port (P1) and the second port (P2)communicate with each other and the third port (P3) and the fourth port(P4) communicate with each other, the cooling operation in which theheat-source-side heat exchanger (12) serves as a condenser and theutilization-side heat exchanger (14) serves as an evaporator isperformed. On the other hand, when the four-way valve (19) is switchedto a second state (see a dashed line in FIG. 28) in which the first port(P1) and the fourth port (P4) communicate with each other and the secondport (P2) and the third port (P3) communicate with each other, theheating operation in which the utilization-side heat exchanger (14)serves as the condenser and the heat-source-side heat exchanger (12)serves as the evaporator is performed.

Part of high-pressure liquid refrigerant flows from the inlet pipe (21,22) connected to an upstream side of the expansion valve (13) into thebranch circuit (10B). Specifically, in the cooling operation, part ofhigh-pressure liquid refrigerant flows into the branch circuit (10B)through the inlet pipe (22) connected to the upstream side of theexpansion valve (13). On the other hand, in the heating operation, partof high-pressure liquid refrigerant flows into the branch circuit (10B)through the inlet pipe (21) connected to the upstream side of theexpansion valve (13).

In the branch circuit (10B), a first opening degree adjuster (52)adjusts the degree of opening of a first throttle valve (18) such thatthe evaporation temperature of refrigerant in a cooler (16) reaches atarget temperature. In addition, a second opening degree adjuster (53)adjusts the degree of opening of a second throttle valve (17) such thatthe degree of superheating of refrigerant at an outlet of the cooler(16) reaches a target degree of superheating. Thus, the temperature ofrefrigerant passing through the cooler (16) can be the targettemperature, and moisturizing of refrigerant to be introduced into thecompressor (11) can be prevented.

In a dew condensation reduction operation control, when a dewcondensation determinator (54) determines that a dew condensation stateis established, occurrence of dew condensation in a power element(s)(37) and the cooler (16) can be reduced by forcibly reducing the degreeof opening of the first throttle valve (18) by a forcible opening degreereducer (55) on behalf of the first opening degree adjuster (52), or byincreasing the temperature of the power element(s) (37) by a temperatureincreaser (91).

According to the foregoing configuration, advantages similar to those ofeach of the foregoing embodiments can be realized in the nineteenthembodiment. According to the nineteenth embodiment, a flow of part ofhigh-pressure liquid refrigerant into the branch circuit (10B) isallowed in both of the cooling operation and the heating operation.Thus, the temperature of the cooler (16) can be easily controlled, andthe dew condensation around the cooler (16) can be easily reduced.

Twentieth Embodiment of the Invention

As illustrated in FIG. 29, a refrigeration apparatus (1) of a twentiethembodiment is configured by changing the configuration of the adjustingmechanism (90) of each of the foregoing embodiments of the presentinvention. Note that the refrigeration apparatus (1) configured bychanging the configuration of the first embodiment is illustrated as anexample in FIG. 29, and the refrigeration apparatus (1) configured bychanging the configuration of the seventh embodiment is illustrated asan example in FIG. 30.

Specifically, an adjusting mechanism (90) includes a capillary tube (27)and a throttle valve (28) which are provided in a branch circuit (10B),and an opening degree adjuster (59) configured to adjust the degree ofopening of the throttle valve (28), instead of including the firstthrottle valve (18), the second throttle valve (17), the first openingdegree adjuster (52), and the second opening degree adjuster (53).

The capillary tube (27) is provided upstream of a cooler (16) of thebranch circuit (10B), and serves as a throttle mechanism of the presentinvention. On the other hand, the throttle valve (28) is provideddownstream of the cooler (16) of the branch circuit (10B).

The opening degree adjuster (59) is provided in a normal operator (51)of an operation control device (50), and adjusts the degree of openingof the throttle valve (28). Specifically, the opening degree adjuster(59) adjusts the degree of opening of the throttle valve (28) such thatthe evaporation temperature of refrigerant in the cooler (16) reaches atarget temperature.

As illustrated in FIG. 29, in the case where the operation controldevice (50) includes a forcible opening degree reducer (55), theforcible opening degree reducer (55) is configured to forcibly reducethe degree of opening of the throttle valve (28) on behalf of theopening degree adjuster (59) when a dew condensation determinator (54)determines that a dew condensation state is established. On the otherhand, as illustrated in FIG. 30, in the case where the operation controldevice (50) includes a temperature increaser (91), the temperatureincreaser (91) is configured similar to that of each of the foregoingembodiments.

In the branch circuit (10B), the opening degree adjuster (59) adjuststhe degree of opening of the throttle valve (28) such that theevaporation temperature of refrigerant in the cooler (16) reaches thetarget temperature. Thus, the temperature of refrigerant passing throughthe cooler (16) is adjusted to the target temperature.

As illustrated in FIG. 29, in a dew condensation reduction operationcontrol, in the case where the operation control device (50) includesthe forcible opening degree reducer (55), the forcible opening degreereducer (55) forcibly reduces the degree of opening of the throttlevalve (28) on behalf of the opening degree adjuster (59) when the dewcondensation determinator (54) determines that the dew condensationstate is established. Thus, a pressure on an upstream side of thethrottle valve (28) is increased, and the amount of refrigerant flowinginto the branch circuit (10B) is decreased. As a result, the amount ofheat absorbed by refrigerant in the cooler (16) is decreased.Consequently, dew condensation in a power module (61) and surroundingcomponents (16, 71) thereof is reduced, and the dew condensation statein the cooler (16) is cleared.

On the other hand, as illustrated in FIG. 30, in the case where theoperation control device (50) includes the temperature increaser (91),when the dew condensation determinator (54) determines that the dewcondensation state is established, the temperature increaser (91)increases the temperature of a power element(s) (37) in a manner similarto that of each of the foregoing embodiments. As a result, the dewcondensation in the power module (61) and the surrounding components(16, 71) thereof is reduced, and the dew condensation state in thecooler (16) is cleared.

According to the foregoing configuration, advantages similar to those ofeach of the foregoing embodiments can be realized in the twentiethembodiment.

Twenty-First Embodiment of the Invention

A refrigeration apparatus (1) of a twenty-first embodiment is configuredsuch that the first opening degree adjuster (52) and the second openingdegree adjuster (53) of each of the first to nineteenth embodimentsrespectively adjust, upon a start of the refrigeration apparatus (1), afirst throttle valve (18) and a second throttle valve (17) to degrees ofopening larger than an opening degree adjustable range of a normaloperation.

Specifically, in the twenty-first embodiment, the first opening degreeadjuster (52) adjusts, upon the start of the refrigeration apparatus(1), the degree of opening of the first throttle valve (18) such thatthe evaporation temperature of refrigerant in a cooler (16) reaches atemperature lower than a predetermined target temperature of the normaloperation. On the other hand, the second opening degree adjuster (53)adjusts, upon the start of the refrigeration apparatus (1), the degreeof opening of the second throttle valve (17) such that the degree ofsuperheating of refrigerant at an outlet of the cooler (16) is smallerthan a predetermined target degree of superheating of the normaloperation. In the foregoing manner, the degrees of opening of the firstthrottle valve (18) and the second throttle valve (17) are larger thanthose of the normal operation upon the start of the refrigerationapparatus (1).

Upon the start of the refrigeration apparatus (1), only liquidrefrigerant does not flow into a branch circuit (10B), but refrigerantcontaining a relatively-large amount of gas refrigerant flows into thebranch circuit (10B). Thus, unevenness in temperature of the cooler (16)is likely to occur, and it is highly likely that a power element(s) (37)cannot be sufficiently cooled. In addition, if the amount of refrigerantflowing into the branch circuit (10B) is small, it takes time forrefrigerant to reach the cooler (16) after the start of therefrigeration apparatus (1), and the power element(s) (37) cannot becooled during such a time.

Since the first opening degree adjuster (52) and the second openingdegree adjuster (53) are configured as described above, the firstopening degree adjuster (52) adjusts, upon the start of therefrigeration apparatus (1), the degree of opening of the first throttlevalve (18) to the degree of opening larger than the opening degreeadjustable range of the normal operation, and the second opening degreeadjuster (53) adjusts, upon the start of the refrigeration apparatus(I), the degree of opening of the second throttle valve (17) to thedegree of opening larger than the opening degree adjustable range of thenormal operation. As a result, since the amount of refrigerant largerthan that in the normal operation can circulate through the branchcircuit (10B) upon the start of the refrigeration apparatus (1), theunevenness in temperature of the cooler (16) can be prevented. Inaddition, after the start of the refrigeration apparatus (1),refrigerant can promptly reach the cooler (16). Thus, the powerelement(s) (37) can be sufficiently cooled right after the start of therefrigeration apparatus (1).

Note that the first opening degree adjuster (52) may be configured to,upon the start of the refrigeration apparatus (1), adjust the degree ofopening of the first throttle valve (18) to a predetermined initialdegree of opening larger than an opening degree adjustable range of thenormal operation. Similarly, the second opening degree adjuster (53) maybe configured to, upon the start of the refrigeration apparatus (1),adjust the degree of opening of the second throttle valve (17) to apredetermined initial degree of opening larger than the opening degreeadjustable range of the normal operation.

As in the twenty-first embodiment, the opening degree adjuster (59) ofthe twentieth embodiment may be configured to, upon the start of therefrigeration apparatus (1), adjust the degree of opening of thethrottle valve (28) larger than the opening degree adjustable range ofthe normal operation.

Twenty-Second Embodiment of the Invention

As illustrated in FIG. 31, a refrigeration apparatus (1) of atwenty-second embodiment is configured by adding, as a closing unitconfigured to close a branch circuit (10B) upon stoppage of therefrigeration apparatus (1), a stop controller (97) to the operationcontrol device (50) of each of the first to nineteenth embodiments andthe twenty-first embodiment. Note that, in FIG. 31, the refrigerationapparatus (1) configured by changing the configuration of the firstembodiment is illustrated as an example.

Specifically, in the twenty-second embodiment, the stop controller (97)is configured to, upon the stoppage of the refrigeration apparatus (1),control the degree of opening of a first throttle valve (18) to afully-closed state on behalf of a first opening degree adjuster (52).Thus, in the twenty-second embodiment, when the stoppage of therefrigeration apparatus (1) is selected, the stop controller (97)controls the degree of opening of the first throttle valve (18) to thefully-closed state.

When the first throttle valve (18) and a second throttle valve (17) areopened upon the stoppage of the refrigeration apparatus (1), refrigerantcontinues flowing until a pressure in the branch circuit (10B) isbalanced. Thus, for a certain time after the stoppage of therefrigeration apparatus (1), refrigerant flows into a cooler (16)although a power element(s) (37) does not generate heat. As a result,there is a possibility that dew condensation occurs in the cooler (16),and therefore the power element(s) (37) is broken down.

However, in the twenty-second embodiment, upon the stoppage of therefrigeration apparatus (1), the stop controller (97) controls thedegree of opening of the first throttle valve (18) to the fully-closedstate. This prevents refrigerant from flowing into the cooler (16) afterthe stoppage of the refrigeration apparatus (1). Thus, a decrease intemperature of the cooler (16) is reduced.

By providing the stop controller (97), the flow of refrigerant into thecooler (16) after the stoppage of the refrigeration apparatus (1) can bereduced. This reduces the decrease in temperature of the cooler (16).Thus, the occurrence of the dew condensation in the cooler (16) can beprevented, and the breakdown of the power element(s) (37) due toadherence of dew condensation water can be prevented. In addition, bycontrolling the second throttle valve (17) provided downstream of thecooler (16) to the fully-closed state, the cooler (16) is not in alow-pressure state after the stoppage of the refrigeration apparatus(1). Thus, the decrease in temperature of the cooler (16) can be furtherreduced. Consequently, the breakdown of the power element(s) (37) can befurther prevented.

Note that the stop controller (97) may be configured to, upon thestoppage of the refrigeration apparatus (1), control the degree ofopening of the second throttle valve (17) to the fully-closed state onbehalf of a second opening degree adjuster (53), or may be configured tocontrol both of the degrees of opening of the first throttle valve (18)and the second throttle valve (17) to the fully-closed state on behalfof the first opening degree adjuster (52) and the second opening degreeadjuster (53).

As in the twenty-second embodiment, the stop controller (97) configuredto, upon the stoppage of the refrigeration apparatus (I), control thedegree of opening of a throttle valve (28) to the fully-closed state onbehalf of an opening degree adjuster (59) may be added to the operationcontrol device (50) of the twentieth embodiment. In such a case,advantages similar to those of each of the foregoing embodiments can berealized.

Twenty-Third Embodiment of the Invention

As illustrated in FIG. 32, a refrigeration apparatus (1) of atwenty-third embodiment is configured such that, in each of the first tonineteenth embodiments and the twenty-first and twenty-secondembodiments, a capillary tube (4) which is a fixed throttle is connectedin parallel to an upstream-side second throttle valve (17) of throttlevalves of a branch circuit (10B). Note that, in FIG. 32, therefrigeration apparatus (1) configured by changing the configuration ofthe first embodiment is illustrated as an example.

The second throttle valve (17) is configured such that the degree ofopening thereof is adjustable by a second opening degree adjuster (53).However, if the second throttle valve (17) is broken down, the degree ofopening thereof cannot be adjusted. Thus, if the degree of opening ofthe second throttle valve (17) is fixed to a relatively-small degree ofopening, the pressure of refrigerant is significantly reduced on anupstream side of a cooler (16). That is, the evaporation pressure ofrefrigerant in the cooler (16) is significantly reduced. For theforegoing reason, there is a possibility that the temperature ofrefrigerant circulating through the cooler (16) is decreased, resultingin excess of a cooling capacity of the cooler (16). In addition, if theflow rate of refrigerant flowing into the cooler (16) is too low, thecooling capacity of the cooler (16) is deficient.

In the twenty-third embodiment, the capillary tube (4) is connected inparallel to the second throttle valve (17) as described above. Thus, ifthe degree of opening of the second throttle valve (17) is fixed to therelatively-small degree of opening due to the breakdown of the secondthrottle valve (17), refrigerant passes through a flow path formed bythe capillary tube (4) and then flows into the cooler (16).Consequently, the extremely-low evaporation pressure of refrigerant inthe cooler (16) is prevented when the second throttle valve (17) isbroken down. This prevents the excess of the cooling capacity of thecooler (16) due to the significant decrease in temperature ofrefrigerant circulating through the cooler (16). In addition, theextremely-low flow rate of refrigerant flowing into the cooler (16) canbe prevented when the second throttle valve (17) is broken down. Thisprevents the deficiency of the cooling capacity of the cooler (16).

Twenty-Fourth Embodiment of the Invention

As illustrated in FIG. 33, a refrigeration apparatus (1) of atwenty-fourth embodiment is configured such that, in each of the firstto twenty-third embodiments, a capillary tube (5) which is a fixedthrottle is connected in series with a downstream-side first throttlevalve (18) (since the throttle valve is designated by the referencenumeral “28” in the twentieth embodiment, hereinafter collectivelyreferred to as a “throttle valve (18, 28)”) of throttle valves of abranch circuit (10B). Note that, in FIG. 33, the refrigeration apparatus(1) configured by changing the configuration of the first embodiment isillustrated as an example.

The throttle valve (18, 28) is configured such that the degree ofopening thereof is adjustable by a first opening degree adjuster (52)(opening degree adjuster (59) in the twentieth embodiment). However, ifthe throttle valve (18, 28) is broken down, the degree of openingthereof cannot be adjusted. Thus, if the degree of opening of thethrottle valve (18, 28) is fixed to a relatively-large degree ofopening, a differential pressure in the throttle valve (18, 28) issignificantly low, and the pressure of refrigerant flowing into a cooler(16) is close to the pressure of refrigerant at an outlet of the branchcircuit (10B). That is, the evaporation pressure of refrigerant in thecooler (16) is significantly reduced. For the foregoing reason, there isa possibility that the temperature of the cooler (16) is decreased,resulting in excess of a cooling capacity of the cooler (16). Inaddition, if the degree of opening of the throttle valve (18, 28) islarge, the amount of refrigerant flowing out from the cooler (16) isincreased. Thus, refrigerant flows out from the cooler (16) beforerefrigerant flowing into the cooler (16) exchanges sufficient heat witha power element(s) (37). That is, refrigerant branched from a main flowuselessly passes through the cooler (16).

In the twenty-fourth embodiment, the capillary tube (5) is connected toa downstream side of the throttle valve (18, 28) as described above.Thus, even if the degree of opening of the throttle valve (18, 28) isfixed to the relatively-large degree of opening due to the breakdown ofthe throttle valve (18, 28), the pressure of refrigerant is reduced bythe capillary tube (5). Consequently, the extremely-low evaporationpressure of refrigerant in the cooler (16) is prevented when thethrottle valve (18, 28) is broken down. This prevents the excess of thecooling capacity of the cooler (16) due to the significant decrease intemperature of refrigerant circulating through the cooler (16). Inaddition, the amount of refrigerant flowing out from the cooler (16) canbe controlled by the capillary tube (5) so as not to be extremely largewhen the throttle valve (18, 28) is broken down. This preventsrefrigerant branched from the main flow from uselessly passing throughthe cooler (16) without the sufficient heat exchange with the powerelement(s) (37).

Twenty-Fifth Embodiment of the Invention

As illustrated in FIG. 34, a refrigeration apparatus (1) of atwenty-fifth embodiment is configured by adding a closing unit of thepresent invention configured to close a branch circuit (10B) upon powershutdown that a power supply to a power supply device (30) is shut downdue to, e.g., a blackout, to the configuration of each of the first tonineteenth embodiments and the twenty-fourth embodiment. Note that, inFIG. 34, the refrigeration apparatus (1) configured by changing theconfiguration of the first embodiment is illustrated as an example.

Specifically, the closing unit is a solenoid valve (6 a) provided in thebranch circuit (10B) and configured to switch to an open state whenpower is ON and switch to a closed state when the power is OFF. Thus, ifthe power supply to the power supply device (30) is shut down due to,e.g., the blackout, the solenoid valve (6 a) switches to the closedstate. In such a manner, the branch circuit (10B) is closed, andrefrigerant no longer circulates.

Upon the power shutdown such as the blackout, since a power supply to apower element(s) (37) is also shut down, the power element(s) (37) nolonger generates heat. On the other hand, if the foregoing closing unitis not provided, the degree of opening of a throttle valve (17, 18, 28)is fixed to a degree of opening upon the power shutdown. Thus, in thebranch circuit (10B), refrigerant continues flowing until a pressure isbalanced. As a result, although the power element(s) (37) does notgenerate heat, refrigerant continues circulating through a cooler (16).Thus, there is a possibility that the temperature of the cooler (16) isdecreased to a temperature at which dew condensation occurs.

In the twenty-fifth embodiment, the branch circuit (10B) is closed bythe solenoid valve (6 a) which is the closing unit upon the powershutdown. Thus, upon the power shutdown such as the blackout, thecirculation of refrigeration through the cooler (16) is blocked, and thedecrease in temperature of the cooler (16) can be reduced. Consequently,the occurrence of the dew condensation can be prevented, and breakdownof the power element(s) (37) due to adherence of dew condensation watercan be prevented.

Since the solenoid valve (6 a) is used as the closing unit, the branchcircuit (10B) can be easily closed.

Twenty-Sixth Embodiment of the Invention

As illustrated in FIG. 35, a refrigeration apparatus (1) of atwenty-sixth embodiment is configured by providing a capacitor (7) and apower shutdown adjuster (6 b) in the refrigeration apparatus (1) of thetwenty-fifth embodiment instead of providing the solenoid valve (6 a).

Specifically, the capacitor (7) is configured to, upon power shutdown,store power generated by rotating a motor (11 a) of a compressor (11)due to inertia. In addition, the power shutdown adjuster (6 b) isconfigured to, upon the power shutdown, adjust the degree of opening ofa throttle valve (18, 28) to a fully-closed state by using power storedin the capacitor (7). Thus, upon the power shutdown, the power shutdownadjuster (6 b) uses power generated by the rotation of the motor (11 a)of the compressor (11) to switch the throttle valve (18, 28) to thefully-closed state. As a result, a branch circuit (10B) is closed, andcirculation of refrigerant through a cooler (16) is blocked.

According to the foregoing configuration, in the twenty-sixthembodiment, the power shutdown adjuster (6 b) switches the throttlevalve (18, 28) to the fully-closed state to close the branch circuit(10B) upon the power shutdown. In such a manner, the circulation ofrefrigerant through the cooler (16) can be blocked, and a decrease intemperature of the cooler (16) can be reduced. Thus, in the twenty-sixthembodiment, occurrence of dew condensation can be prevented, andbreakdown of a power element(s) (37) due to adherence of dewcondensation water can be prevented.

Note that, in the twenty-sixth embodiment, the power shutdown adjuster(6 b) may control the degree of opening of a second throttle valve (17)to the fully-closed state upon the power shutdown. In such a case, thesimilar advantages can be realized.

In addition, the capacitor (7) may be configured to, upon the powershutdown, store power generated by reversely rotating the motor (11 a)of the compressor (11) due to a pressure difference of refrigerant.

Twenty-Seventh Embodiment of the Invention

As illustrated in FIG. 36, a refrigeration apparatus (1) of atwenty-seventh embodiment is configured by adding a pump-down controller(98) configured to perform a pump-down operation in which refrigerant isstored in a heat-source-side heat exchanger (12), to the operationcontrol device (50) of each of the first to twenty-sixth embodiments.Note that, in FIG. 36, the refrigeration apparatus (1) configured bychanging the configuration of the first embodiment is illustrated as anexample.

Specifically, the pump-down controller (98) is configured to perform thepump-down operation in which refrigerant is stored in theheat-source-side heat exchanger (12) by switching an expansion valve(13) to a fully-closed state and switching a throttle valve (a firstthrottle valve (18) or a throttle valve (28)) to the fully-closed state.In addition, the pump-down controller (98) includes a timer configuredto measure a time from a preset start point of the pump-down operationto an overheating point bringing about a overheating state in which thetemperature of a power element(s) (37) is highly likely to exceed apredetermined upper limit. The pump-down controller (98) completes thepump-down operation before termination of the time measurement by thetimer. More specifically, the pump-down controller (98) changes therotational speed of a motor (11 a) of a compressor (11) such that thepump-down operation is completed before the termination of the timemeasurement by the timer.

When the pump-down operation is performed, the throttle valve (18, 28)is switched to the fully-closed state to close a branch circuit (10B).Thus, refrigerant no longer flows into a cooler (16). Although the powerelement(s) (37) cannot be cooled by the cooler (16) and the temperatureof the power element(s) (37) is increased, refrigerant does not flowinto the cooler (16), and therefore the overheating state of the powerelement(s) (37) cannot be estimated based on a refrigerant state. As aresult, there is a possibility that the power element(s) (37) enters theoverheating state during the pump-down operation, resulting in breakdownof the power element(s) (37).

In the twenty-seventh embodiment, the pump-down controller (98) isconfigured to perform the pump-down operation, i.e., to estimate theoverheating point at which the power element(s) (37) enters theoverheating state during the pump-down operation and complete thepump-down operation before the overheating point. Thus, since thepump-down operation can be completed before the power element(s) (37)enters the overheating state, the breakdown of the power element(s) (37)can be prevented, and it can be ensured that the pump-down operation isperformed.

Note that the pump-down controller (98) may include an estimatorconfigured to estimate the overheating point based on the heat capacityand heat generation amount of the power element(s) (37) which are inputto the estimator, instead of including the timer.

Twenty-Eighth Embodiment of the Invention

As illustrated in FIG. 37, a refrigeration apparatus (1) of atwenty-eighth embodiment is configured by adding a start interruptingunit configured to interrupt a start of the refrigeration apparatus (1)when due condensation is highly likely to occur in a cooler (16), to theconfiguration of each of the first to twenty-seventh embodiments. Notethat, in FIG. 37, the refrigeration apparatus (1) configured by changingthe configuration of the first embodiment is illustrated as an example.

Specifically, the start interrupting unit includes a temperature switch(99) configured to interrupt the start of the refrigeration apparatus(1) when the temperature of the cooler (16) is equal to or lower than apredetermined lower limit. The temperature switch (99) is attached tothe cooler (16) and is connected to an operation control device (50).The temperature switch (99) detects the temperature of the cooler (16),and interrupts the start of the refrigeration apparatus (1) bytransmitting a start interrupting signal to the operation control device(50). Note that the predetermined lower limit is set to a temperature atwhich the dew condensation is highly likely to occur in the cooler (16).

Upon stoppage of the refrigeration apparatus (1), the dew condensationmay be highly likely to occur in the cooler (16) depending on, e.g., achange in environment. If the refrigeration apparatus (1) is started insuch a state, there is a possibility that a short circuit is caused in,e.g., an electrical connection part of a power element(s) (37).

However, in the twenty-eighth embodiment, the temperature switch (99) isprovided. Thus, if the dew condensation is highly likely to occur in thecooler (16), the temperature switch (99) interrupts the start of therefrigeration apparatus (1). Since the temperature switch (99)interrupts the start of the refrigeration apparatus (1) when the dewcondensation is highly likely to occur in the cooler (16), the shortcircuit in, e.g., the electrical connection part of the power element(s)(37) upon the start of the refrigeration apparatus (1) can be prevented.In other words, the start of the refrigeration apparatus (1) is allowedonly when there is no possibility that the short circuit is caused,thereby ensuring safety upon the start of the refrigeration apparatus(1).

Note that the start interrupting unit of the present invention is notlimited to the temperature switch (99). Any units may be employed aslong as the unit can detect, before the start of the refrigerationapparatus (1), whether or not the dew condensation is highly likely tooccur in the cooler (16) and can interrupt the start of therefrigeration apparatus (1) when it is determined that the dewcondensation is highly likely to occur.

Other Embodiment

Each of the foregoing embodiments may have the following configurations.

In the twentieth embodiment, the throttle mechanism (e.g., the capillarytube (27)) of the present invention is provided upstream of the cooler(16) of the branch circuit (10B), and the throttle valve (28) of thepresent invention is provided downstream of the cooler (16). However,the throttle mechanism (27) and the throttle valve (28) may be arrangedin reversed positions. In such a case, the opening degree adjuster (59)is configured to, in the normal operation, adjust the degree of openingof the throttle valve such that the evaporation temperature ofrefrigerant in the cooler (16) reaches a target temperature.

According to the foregoing configuration, the opening degree adjuster(59) adjusts the degree of opening of the throttle valve (28), andcontrols the evaporation temperature of refrigerant in the cooler (16)to the target temperature. On the other hand, when the dew condensationdeterminator (54) determines that the dew condensation state isestablished, the forcible opening degree reducer (55) forcibly reducesthe degree of opening of the throttle valve (28) by a predeterminedamount on behalf of the opening degree adjuster (59). Thus, the amountof refrigerant flowing into the branch circuit (10B) is decreased, andtherefore the amount of heat absorbed by refrigerant in the cooler (16)(the amount of heat dissipated from the power module (61)) is decreased.As a result, the dew condensation in the power module (61) and thesurrounding components (16, 71) thereof is reduced, and the dewcondensation state in the cooler (16) is cleared.

Even in the foregoing configuration, since the temperature ofrefrigerant passing through the cooler (16) is adjustable by providingthe adjusting mechanism (90) (the throttle valve (28), the capillarytube (27), or the opening degree adjuster (59)), the temperature of thecooler (16) can be adjusted to a suitable temperature. That is, thetemperature of refrigerant passing through the cooler (16) can beadjusted depending on the amount of heat generation of the powerelement(s) (37) and the change in installation environment of the powerelement(s) (37). Thus, insufficient cooling or excessive cooling of thepower element(s) (37) by the cooler (16) can be reduced, therebyimproving efficiency of cooling of the power element(s) (37) by thecooler (16).

Note that the foregoing embodiments have been set forth merely forpurposes of preferred examples in nature, and are not intended to limitthe scope, applications, and use of the invention.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful as the refrigerationapparatus in which the power element(s) of the power supply deviceconfigured to supply power to the components of the refrigerant circuitis cooled by refrigerant.

DESCRIPTION OF REFERENCE CHARACTERS

-   1 Refrigeration Apparatus-   4 Capillary Tube (Fixed Throttle)-   5 Capillary Tube (Fixed Throttle)-   6 Closing Unit-   6 a Solenoid Valve-   6 b Power Shutdown Adjuster (Power Shutdown Adjusting Unit)-   10 Refrigerant Circuit-   10A Main Circuit-   10B Branch Circuit-   11 Compressor-   12 Heat-Source-Side Heat Exchanger-   13 Expansion Valve (Expansion Mechanism)-   14 Utilization-Side Heat Exchanger-   16 Cooler-   17 Second Throttle Valve (Throttle Mechanism)-   18 First Throttle Valve (Throttle Valve)-   27 Capillary Tube (Throttle Mechanism)-   28 Throttle Valve-   30 Power Supply Device-   37 Power Element-   41 Outdoor Air Temperature Sensor (Air Temperature Sensor)-   42 Room Temperature Sensor-   43 Evaporation Temperature Sensor-   44 Outlet Temperature Sensor-   45 Dew Condensation Sensor-   46 Temperature Sensor-   47 Humidity Sensor-   48 Humidity Sensor-   52 First Opening Degree Adjuster (Opening Degree Adjuster)-   53 Second Opening Degree Adjuster (Throttle Mechanism Adjuster)-   54 Dew Condensation Determinator-   55 Forcible Opening Degree Reducer-   56 Heat Generation Amount Increaser-   57 Heat Generation Amount Resetter-   58 Forcible Heat Generation Amount Resetter-   59 Opening Degree Adjuster-   90 Refrigerant Temperature Adjusting Mechanism-   91 Temperature Increaser-   92 Temperature Resetter-   95 Heater-   97 Stop Controller-   98 Pump-Down Controller-   99 Temperature Switch (Start Interrupting Unit)

1. A refrigeration apparatus including a refrigerant circuit having amain circuit in which a compressor, a heat-source-side heat exchanger,an expansion mechanism, and a utilization-side heat exchanger areconnected together to perform a refrigeration cycle, a branch circuitwhich branches part of high-pressure liquid refrigerant flowing throughthe main circuit and leads the part of high-pressure liquid refrigerantfrom a high-pressure part of the main circuit to part of the maincircuit having a pressure lower than that of the high-pressure part, apower supply device including a power element and supplying power to adriver of a component of the refrigerant circuit, and a cooler connectedto the branch circuit and cooling the power element by refrigerantflowing through the branch circuit, the refrigeration apparatuscomprising: an adjusting mechanism configured to adjust a state ofrefrigerant flowing through the branch circuit and adjust a temperatureof refrigerant passing through the cooler to a target temperature. 2.The refrigeration apparatus of claim 1, wherein the adjusting mechanismincludes a throttle mechanism connected to one end of the cooler of thebranch circuit, a throttle valve which is connected to the other end ofthe cooler of the branch circuit and a degree of opening of which isadjustable, and an opening degree adjuster adjusting the degree ofopening of the throttle valve such that an evaporation temperature ofrefrigerant in the cooler reaches a target temperature.
 3. Therefrigeration apparatus of claim 2, wherein the throttle valve isprovided downstream of the cooler, the throttle mechanism is providedupstream of the cooler, and a degree of opening of the throttlemechanism is adjustable, and the adjusting mechanism further includes athrottle mechanism adjuster adjusting the degree of opening of thethrottle mechanism such that a degree of superheating of refrigerant atan outlet of the cooler reaches a target degree of superheating.
 4. Therefrigeration apparatus of claim 3, wherein the opening degree adjusteradjusts, upon a start of the refrigeration apparatus, the degree ofopening of the throttle valve to a degree of opening larger than anopening degree adjustable range of a normal operation, and the throttlemechanism adjuster adjusts, upon the start of the refrigerationapparatus, the degree of opening of the throttle mechanism to a degreeof opening larger than the opening degree adjustable range of the normaloperation.
 5. The refrigeration apparatus of claim 3, furthercomprising: a stop controller configured to, upon stoppage of therefrigeration apparatus, control at least one of the degrees of openingof the throttle valve and the throttle mechanism to a fully-closedstate.
 6. The refrigeration apparatus of claim 3, further comprising: afixed throttle connected in parallel to the throttle mechanism.
 7. Therefrigeration apparatus of claim 3, further comprising: a fixed throttleconnected in series with the first throttle valve.
 8. The refrigerationapparatus of claim 2, further comprising: a detector configured todetect a physical amount to be an indicator for a possibility ofoccurrence of dew condensation in the power element or a surroundingcomponent thereof; and a forcible opening degree reducer configured to,when a detection value of the detector indicates a dew condensationstate in which the dew condensation is highly likely to occur in thepower element or the surrounding component thereof, forcibly reduce thedegree of opening of the throttle valve on behalf of the opening degreeadjuster.
 9. The refrigeration apparatus of claim 8, wherein thedetector includes a temperature sensor provided in the power element orthe surrounding component thereof, and an air temperature sensordetecting a temperature of air around the power supply device, and theforcible opening degree reducer is configured to, when the detectionvalue of the temperature sensor is lower than the detection value of theair temperature sensor and it is determined that the dew condensationstate is established, forcibly reduce the degree of opening of thethrottle valve on behalf of the opening degree adjuster.
 10. Therefrigeration apparatus of claim 8, wherein the detector includes atemperature sensor provided in the power element or the surroundingcomponent thereof, and an air temperature sensor detecting a temperatureof air around the power supply device, and the forcible opening degreereducer is configured to, when a temperature obtained by adding a presettemperature increase from an installation part of the temperature sensorto an electrical connection part of the power element to the detectionvalue of the temperature sensor is lower than the detection value of theair temperature sensor and it is determined that the dew condensationstate is established, forcibly reduce the degree of opening of thethrottle valve on behalf of the opening degree adjuster.
 11. Therefrigeration apparatus of claim 8, wherein the detector includes atemperature sensor provided in the power element or the surroundingcomponent thereof, and an air temperature sensor detecting a temperatureof air around the power supply device, and the forcible opening degreereducer is configured to, when the detection value of the temperaturesensor is lower than a dew-point temperature corresponding to a presetreference relative humidity at an air temperature detected by the airtemperature sensor and it is determined that the dew condensation stateis established, forcibly reduce the degree of opening of the throttlevalve on behalf of the opening degree adjuster.
 12. The refrigerationapparatus of claim 8, wherein the detector includes a humidity sensordetecting a relative humidity of air around the power element, and theforcible opening degree reducer is configured to, when the detectionvalue of the humidity sensor is higher than a predetermined upper limitand it is determined that the dew condensation state is established,forcibly reduce the degree of opening of the throttle valve on behalf ofthe opening degree adjuster.
 13. The refrigeration apparatus of claim 8,wherein the detector includes a humidity sensor detecting a relativehumidity of air around the power supply device, an air temperaturesensor detecting a temperature of air around the power supply device,and a temperature sensor provided in the power element or thesurrounding component thereof, and the forcible opening degree reduceris configured to, when the detection value of the temperature sensor islower than a dew-point temperature calculated based on the relativehumidity detected by the humidity sensor and the air temperaturedetected by the air temperature sensor, forcibly reduce the degree ofopening of the throttle valve on behalf of the opening degree adjuster.14. The refrigeration apparatus of claim 2, further comprising: a dewcondensation sensor detecting dew condensation in the power element orthe surrounding component thereof; and a forcible opening degree reducerconfigured to, when a detection value of the dew condensation sensorindicates a dew condensation state in which dew condensation occurs inthe power element or the surrounding component thereof, forcibly reducethe degree of opening of the throttle valve on behalf of the openingdegree adjuster.
 15. The refrigeration apparatus of claim 1, furthercomprising: a closing unit configured to close the branch circuit uponpower shutdown that a power supply to the power supply device is shutdown.
 16. The refrigeration apparatus of claim 15, wherein the closingunit is configured by a solenoid valve provided in the branch circuitand switching to a closed state upon the power shutdown.
 17. Therefrigeration apparatus of claim 3, further comprising: a power shutdownadjusting unit configured to, upon power shutdown that a power supply tothe power supply device is shut down, use power generated in a driver ofthe compressor by rotation of the compressor to adjust at least one ofthe degrees of opening of the throttle valve and the throttle mechanismto a fully-closed state.
 18. The refrigeration apparatus of claim 1,further comprising: a pump-down controller configured to control theexpansion mechanism and at least one of the throttle valve and thethrottle mechanism to the fully-closed state to perform a pump-downoperation in which refrigerant is stored in the heat-source-side heatexchanger, and estimate an overheating point bringing about anoverheating state in which a temperature of the power element is highlylikely to exceed a predetermined upper limit to complete the pump-downoperation before the overheating point.
 19. The refrigeration apparatusof claim 1, further comprising: a start interrupting unit configured to,when the dew condensation is highly likely to occur in the cooler,interrupt the start of the refrigeration apparatus.
 20. Therefrigeration apparatus of claim 2, further comprising: a detectorconfigured to detect a physical amount to be an indicator for apossibility of occurrence of dew condensation in the power element or asurrounding component thereof; and a temperature increaser configuredto, when a detection value of the detector indicates a dew condensationstate in which the dew condensation is highly likely to occur in thepower element or the surrounding component thereof, increase atemperature of the power element.
 21. The refrigeration apparatus ofclaim 20, wherein the detector includes a temperature sensor provided inthe power element or the surrounding component thereof, and an airtemperature sensor detecting a temperature of air around the powersupply device, and the temperature increaser is configured to, when thedetection value of the temperature sensor is lower than the detectionvalue of the air temperature sensor and it is determined that the dewcondensation state is established, increase the temperature of the powerelement.
 22. The refrigeration apparatus of claim 20, wherein thedetector includes a temperature sensor provided in the power element orthe surrounding component thereof, and an air temperature sensordetecting a temperature of air around the power supply device, and thetemperature increaser is configured to, when a temperature obtained byadding a preset temperature increase from an installation part of thetemperature sensor to an electrical connection part of the power elementto the detection value of the temperature sensor is lower than thedetection value of the air temperature sensor and it is determined thatthe dew condensation state is established, increase the temperature ofpower element.
 23. The refrigeration apparatus of claim 20, wherein thedetector includes a temperature sensor provided in the power element orthe surrounding component thereof, and an air temperature sensordetecting a temperature of air around the power supply device, and thetemperature increaser is configured to, when the detection value of thetemperature sensor is lower than a dew-point temperature correspondingto a preset reference relative humidity at an air temperature detectedby the air temperature sensor and it is determined that the dewcondensation state is established, increase the temperature of the powerelement.
 24. The refrigeration apparatus of claim 20, wherein thedetector includes a humidity sensor detecting a relative humidity of airaround the power element, and the temperature increaser is configuredto, when the detection value of the humidity sensor is higher than apredetermined upper limit and it is determined that the dew condensationstate is established, increase the temperature of the power element. 25.The refrigeration apparatus of claim 20, wherein the detector includes ahumidity sensor detecting a relative humidity of air around the powersupply device, an air temperature sensor detecting a temperature of airaround the power supply device, and a temperature sensor provided in thepower element or the surrounding component thereof, and the temperatureincreaser is configured to, when the detection value of the temperaturesensor is lower than a dew-point temperature calculated based on therelative humidity detected by the humidity sensor and the airtemperature detected by the air temperature sensor and it is determinedthat the dew condensation state is established, increase the temperatureof the power element.
 26. The refrigeration apparatus of claim 2,further comprising: a dew condensation sensor detecting dew condensationin the power element or the surrounding component thereof; and atemperature increaser configured to, when a detection value of the dewcondensation sensor indicates a dew condensation state in which dewcondensation occurs in the power element or the surrounding componentthereof, increase a temperature of the power element.
 27. Therefrigeration apparatus of claim 20, wherein the temperature increaserincludes a heat generation amount increaser increasing an amount of heatgeneration of the power element.
 28. The refrigeration apparatus ofclaim 20, wherein the temperature increaser includes a heater heatingthe power element.
 29. The refrigeration apparatus of claim 27, furthercomprising: a heat generation amount resetter configured to, when thedew condensation state is cleared, reset the amount of heat generationof the power element increased by the heat generation amount increaserto a normal state before an increase in heat generation amount.
 30. Therefrigeration apparatus of claim 29, further comprising: a forcible heatgeneration amount resetter configured to, after a predetermined time haslapsed since the amount of heat generation of the power element isincreased by the heat generation amount increaser, forcibly reset theamount of heat generation of the power element increased by the heatgeneration amount increaser to the normal state before the increase inheat generation amount.
 31. The refrigeration apparatus of claim 27,wherein the heat generation amount increaser increases a current valueof the compressor to increase the amount of heat generation of the powerelement controlling the compressor.
 32. The refrigeration apparatus ofclaim 27, wherein the power element is a switching element, and the heatgeneration amount increaser increases a switching frequency of theswitching element to increase the amount of heat generation of the powerelement.
 33. The refrigeration apparatus of claim 27, wherein the powerelement is a switching element, and the heat generation amount increaserincreases a loss of the switching element to increase the amount of heatgeneration of the power element.
 34. The refrigeration apparatus ofclaim 27, wherein the heat generation amount increaser increases aconduction loss of the power element to increase the amount of heatgeneration of the power element.